Anyone else feel guilty at work when you're between projects or waiting for a request to be completed?

I usually teach myself something new in that time, but I feel guilty.

During that time I work on improving documentation and doing security assessments of features. Nothing to be guilty about unless you're going out of your way to not do something. Teaching yourself something new is good. Document it so other people can learn from you.

I understand that feeling but think of it as recharge time for when work is super hectic if you always load yourself up on stuff then you will burn out or get sick.

Learning new stuff is the best way to add value to the company cause they are paying you for your skills before you leanrt that new thing and you are able to provide them that new capability for free (at least until your next pay meeting ;) ) .

Free time? Between tasks? Never heard of them.

I know that guilt. I've been teaching myself nodeJS this week. Written a dummy hop based payment provider in between support tickets. Peak-shmeak

I'm learning about our version control system because no one else would.
Imagine the productivity once we know how to branch, merge and rollback.