I agree with you that a 1 hour meeting probably shouldn't ruin your whole day, but I also feel like it can take a fair bit of time to essentially reload the problem I've been working on back into my brain if it happens to be a fairly complex one. This is compounded if it's an actual meaty technical meeting because not only do I lose my train of thought but I have to start a while bunch of other ones and also attempt to jot them down before returning to where I was.
Sounds like you've been at this significantly longer than me, maybe context switching is a skill I just haven't acquired yet...