You hit the nail on the head.

After work drinks on Friday are enjoyable because they're informal and not (usually) arranged as a company initiative. It's a chance to let off the work related stress with a group of people in a similar situation while being on neutral territory.

Don't want to come to Friday after work drinks? Sweet, have a good afternoon. I'll be smashing a pint with/without you.

Friday Zoom drinks from 5-6PM can die. No, I don't want to sit in a quasi-optional meeting with 25 people arranged by HR/management. It's not comparable to shooting the shit with a selection of staff that have formed a connection organically.

The best way to determine the success/failure of Friday drinks is the percentage of people still present at 6:05PM. It's at least 50% below the 5:55PM number. At a local bar/pub, it's pretty stable until 7-8 and you're usually an hour past talking pure "work" shit.

</rant>