I think the anticipation of interruption caused by meetings might be worse, I end up losing a half hour on both ends.

This is what kills my days. Other interruptions from coworkers usually are on topic and it’s always a pleasure to help out.

Oh how I hate a last minute rescheduling of a meeting. Feeling like I only have 30 minutes, I didn't start anything deep. Such a waste.

Pre-pandemic, I tended to keep an erratic home-work/office-work schedule. Sometimes I would be at home working, and then leave to go to the office for a meeting, but I'd arrive a half hour before the meeting was to start. That time turned out to be mostly wasted. There was no way I was going to get any deep work done in that time. Sure, sometimes I could do some idle research, stuff that I could get into and out of quickly, but largely it was wasted time.

I could have just spent all my time in the office, but the open office plan environment is not conducive to deep work, even without direct interruptions (which there would be, too).

I guess the best solution for me would have been to arrive at the office 5-10 minutes before the meeting start time, but it was surprisingly hard to get that right, even with a predictable commute time (bus or walking).

On top of all that, I would occasionally completely miss meetings if I was in a flow state before that. I would somehow miss desktop and phone notifications that a meeting was coming up. I guess the solution to that would have been to set an actual alarm on my phone, something that I couldn't ignore, but I never ended up doing that for some reason.

Yep. For me, a meeting is half a day lost.

Oh, half an hour till that meeting, better not start anything serious.

And some smartypants will schedule meetings with 1h gaps between so absolutely nothing will get done