Watch Strap parted & watch was lost

1/ never

2/ see 1. But I have had my watch for 5months, i see you are asking specifically about new watches. 

Clearly never is not true, happened to me, just warning people to be carfull, had my last watch for 20 years this one fell of in 20 days

Wow. Just wow. YOU lose the watch, and it's Garmin's poor customer service that is the issue????

The sense of entitlement and absence of personal responsibility in this just leaves me speechless.

Never had any problem with any Garmin watch band in 15 years. I swim, bike and run. 

I’d suggest that if you were wearing it over a jacket that you did not secure it properly.

I do not see how you can hold Garmin to account.

Never had any problems with my 945 watch band. 

Wow, I think you miss the point, I have a brand new Garmin watch my first ever sports watch, buckle it on as normal secured with strap and toggle on my wrist under my coat and glove and two hours later it has fallen off. What possible reasons are there?

1/ I didn't secure the strap properly and it fell off, but I know I did.

2/ The buckle or strap parted and the watch dropped off.

If 1 is true than I am warning people to take care themselves because it is therefore possible to not strap it on securely. Equally from your answers it seems it is a rare occurrence or even never happened, therefore makes it unlikely that not securing the strap is the reason the watch was lost.

However you look at it Garmin cannot say there was not ever, never, totally impossible, that the strap might have failed.

When you have eliminated the impossible, whatever remains, however improbable, must be the truth.

So what it comes down to is one of the above two scenarios. Feel free to get on your high horse but check your watch strap and buckle first!!!

Garmin customer services won't talk to me about it without the watch, don't have the watch. but if 2 is true than that's isn't great customer service (in my view)

When you have eliminated the impossible, whatever remains, however improbable, must be the truth.

Don't take offense, but look at it from the our view.  What you've posted is highly improbable for several reasons.  If we except that you fastened the watch correctly, then we are left with the watch band disconnected for some unknown reason (which there are zero post of this happening in the past), you had no "falls or scraps", and without you noticing, the watch came off your wrist and worked it's way from under your coat and glove.  You say you're new to Garmin.  Do you know how many post there have been about watch lenses cracking or scratching that have never been dropped, bumped or scraped against anything?  They just appeared for no reason at all.  I'm not calling you a liar by no means, but it's more probable there was an event you don't recall that caused you to lose your watch regardless of how sure you may feel that wasn't the case.

Well, in my experience the FR-945 band seems to be way better (softer, with less deep grooves that leads to breaks) than, for example, FR-920 (5 years, 5 -expensive- bands, they've always broken in the same place. At the contrary, my Polar 625X has the same band after 15 years. I also have a special award for all my Casio watches, their bands last at least 5 years). 

indeed, these new bands are silicone-based, that's the difference...