Why are the Fenix 8 data fonts so small?

Yeah, I think part of what affects drain in Portal (or any other face) is what fields you choose.  If you have numerous dynamic fields requiring update, such as HR, seconds counter in time, etc., those updates/refreshes will use cycles, quite a few of them.

I'm not using AOD (thought I'd miss this on the F8 but I find I rarely do), 51mm AMOLED, 2/3 brightness with an 8 hour sleep cycle as well. I'm on 15.32, so quite a big difference there.

I debated quite a bit about the 47 vs 51mm, but ultimately I decided I was okay with a bit larger/heavier watch, in exchange for what I consider great battery life.  The 24mm lugs/band help a lot in this regard, I find.

thanks for sharing your experiences. I've held back on FW15 due to all the reports of laggy-ness which I would hate to see return (I witnessed that with the firmware that came with the watch but am happy with the performance of 13.35...not to mention I get to keep the battery saver mode for sleeping which got removed in FW15)

Yeah, I saw those reports, but I haven't experienced this at all (as a most-ex OS s/w engineer I'm fairly sensitive to any sort of latency issues... ;-]), since updating.

I use the standard Sleep Focus Mode, where it changes the face to Sleep (works fine in 15.x), so this isn't much of an impact in my use-case.

No, I just use the Free training plan when doing Strength Training, no timer (so no beeps).

I keep my BT and Wireless disabled, and use Quick Settings to enable for syncs. The watch technically keeps BT on anyway, unless you go through and disable all linked Sensors and such (I use an external HR for rides, for example).  I generally see a drain of 1-2% overnight, regardless of what I've got enabled though, the 51mm seems to be in soomewhat of a class by itself, IME.

I wonder though, have you tried a couple of nights w/o the battery monitoring s/w?  I'm wary of these (I was an OS s/w engineer for some years, mostly former at this point), as doing constant interrupts to monitor/log battery in a way that's not OEM (I'm not familiar with the Garmin API set, to know if you can hook into their battery monitoring stack), can be pretty detrimental in terms of CPU/storage and battery, IME.  I tried one of these on my F7 (after reading a bunch of reviews about how the impact was nominal, on a couple of them) and it was a pretty poor experience, in this regard...

great thoughts and I'm enjoying your comments/discussion.

battery monitoring: I'm using Battery Graph which I did test a long time ago whether or not it was using a lot of battery on my Forerunner (either 945LTE or 955) and I found it to be negligible. that being said, your comment made me think I should remove it at some point because I really don't utilize it. I've been tracking my battery usage manually to hone in on different watch faces and their performance.

as for BT off vs not, I do see a slight uptick in usage but nothing drastic. again a hair under 1.5% to about 2% overnight if I leave BT on (I have wifi off all the time).

the 51mm is indeed in a class by itself for battery endurance, but just is a bit too large for my wrist size. I've worn 47mm Garmin watches for a long time, and thankfully, the extra weight of the Fenix over the Forerunner wasn't too big an adjustment (I do occasionally notice it and just this weekend, I tried on a friend's 965 and the difference was very noticeable (not surprising)). 

I'm probably being ignorant/obtuse: but can you explain what you you mean by Quick Settings for syncs. are you talking about a hot key or something via Controls?

I don't have notifications pop on my screen, but I usually leave on BT so I can consult what notifications exist if I desire to without having to pull my phone out of my pocket. (I have minimal notifications sent to my iPhone screen as it is).