Which second Garmin watch?

I don't know that your watch really needs to "rest" but if you want to have a second watch, that doesn't look like a sports watch, for more casual use the VA3 is more than suitable for that. In my opinion though the 1 button + touchscreen interface is really poor for any running other than just start>run>stop types of run.

Initially when it looked like there wasn't going to be much done appearance-wise with the Forerunner line after the 935 came out I bought the VA3 to use as a daily wear/casual watch and kept using my 735 for all of my runs/rides/workouts. And I was perfectly happy with that arrangement, for a while. Eventually it became a bit of a hassle trying to make sure both watches always had enough of a charge and when the 645 came out I jumped on it and wear it almost exclusively.

I do still keep the VA3 in a charged state and will wear it to work or when I go out if I see that the charge is getting low on my 645. I put the 645 on the charger and wear the VA3 until the next time I have a workout planned. While my 735 is also keep charged as I use that as a head unit on my bike. Which kind of makes my statement about keeping 2 watches charged sound silly, but I'm not constantly switching among these 3 watches the way I was doing before.

forerunner 735XT
the instinct does not support running dynamics and HR swimming

I don't know that your watch really needs to "rest" but if you want to have a second watch, that doesn't look like a sports watch, for more casual use the VA3 is more than suitable for that. In my opinion though the 1 button + touchscreen interface is really poor for any running other than just start>run>stop types of run.

Initially when it looked like there wasn't going to be much done appearance-wise with the Forerunner line after the 935 came out I bought the VA3 to use as a daily wear/casual watch and kept using my 735 for all of my runs/rides/workouts. And I was perfectly happy with that arrangement, for a while. Eventually it became a bit of a hassle trying to make sure both watches always had enough of a charge and when the 645 came out I jumped on it and wear it almost exclusively.

I do still keep the VA3 in a charged state and will wear it to work or when I go out if I see that the charge is getting low on my 645. I put the 645 on the charger and wear the VA3 until the next time I have a workout planned. While my 735 is also keep charged as I use that as a head unit on my bike. Which kind of makes my statement about keeping 2 watches charged sound silly, but I'm not constantly switching among these 3 watches the way I was doing before.

Mine FR935 is a refurbished one. The first one was bought in July. At the end of october, the optical HR appeared with a fissure, out of nowhere (no agression). I always had extreme care. I used it 24hx7, running and swiming mostly twice a week and some OWS in summer.

Garmin just replaced it imediatly (in a week), "but" for a refurbished one. I also think that it is designed to be used exhaustively (or should be), but as every thing, it isn't 100% and long time "wear proof". So, this is why i think it need some "rest".

As you, I see VA3 as daily wear/casual alternative, that also could be used for training.

And about "True Up", it works?

forerunner 735XT
the instinct does not support running dynamics and HR swimming

I will analyze 735XT.

Running Dynamics, i think i could live with out, for a run or two.
HR swimming also, because my swimming is yet a lower intermediate level, mostly on classes. I'll start now with free 50m swimming on my own, but for that a i could use the 935 and leave the second watch for classes.

Apple Watch 4 works well enough when needed. Otherwise I use my Garmin for tracking activities, and AW for anything else.

I second on the Apple Watch!

This thread highlights some concerns for the 935. It seems much more reliable than the Fenix range, yet clearly it has problems with wear. My optical sensor has also been damaged through no misuse whatsoever.

Should you go and buy another $500+ watch just to one or both do not wear out so fast? It sounds crazy to do this, in my own opinion. The Apple Watch isn't very good for running, but is an all rounder with limited battery life, so you are comparing apples and pears.

Here is a wildcard response for you: Use your 935 to destruction. When it fails, don't buy a new one, as much as any company would love you to buy a good that can't last the long term only for you to go back repeatedly and buy more of their products.

Incidentally, a Garmin Vivoactive original works fine for swimming (unlike the VivoactiveHR, which is destroyed by swimming) and fulfils 90% of what I really need. Some good points: If optical heart rate is known as sketchy, why bother with it at all? If instant pace is sketchy, why bother with it at all? If the barometer is far more variable in performance when compared to other watch brands, why bother with it at all? You see my point here, I am sure. The 935 disappointed me overall because it can't last the long haul for the higher price. If I had a Fenix I would also be angry, given the known issues with that watch. I find it ironic I can return to a watch from 4 years ago and have almost as good capability in a reliable manner for running and GPS tracking.

But wait, you say, what about X Y and Z? What of VO2 max? Answer: Do your own VO2 Max reliable test as us coaches have dictated for years, it's the only true reliable test!
What of the conditioning/performance features of the 935? Answer: They are just guesses, shown not to be all that reliable.

The 935 watch is far better than the Fenix range and is a Fenix5'plastic' that seems to work well in most ways. But it's supposed to be a traithlon watch yet it can't handle open water swimming due to faulty OHR covers, bad open water swimming GPS tracks, and the barometer/altimeter eventually breaks if you swim regularly in an indoor pool.

My final advice is: use an older watch from Garmin or another that gets the basics correct and avoids gimmicks. If I'm using more than 13 hours GPS I have to carry a charger, but with no OHR on the Vivoactive I don't care about this, as it can sit in my pocket on a long hike. Let us not get carried away by people buying two or three watches just because one is not robust enough!

I had a 935. Than the barometer went down. Garmin replaced with a new 935 but I started making a lot of questions...like YOU. And now I also have an Instinct. And the reasons are the same of yours. I use Instinct some rest days and in the swimming pool 2-3 times a week. The main difference is the monitor, but during swim I only use distance and time and the monitor is good with these 2 datas.
I think I will use a lot my Instinct during my summer job (I'm a mid mountain guide) and I need altimeter and time...and watch...daytime of course!
So I think i'll go on using 935 for every run workout, but using another watch I hope to increase the 935 life.
Have a good swim, bike and run!

I've used my 935 24/7 (actually about 16/7 since I don't sleep with it) and haven't noticed any wear issues. I've tried some other watches like the F5+ but always go back to the 935. I also do have an older 630 but haven't seen a reason to use it since I got my 935 1.5 years ago. I've played with my wife's VAHR but far prefer the 935. So I'm not quite sure why your 935 needs a "rest".