Time you spend sitting at a table need not be wasted.
Personally, I have a nonfiction book out of the library at all times. If I have to spend 20 minutes sitting at a table, then it's going to be 20 minutes spent reading, not just waiting.
There are other things you can take with you which can be used to increase the baseline value of the time you spend between other activities.
This is the public group instrumental rationality diary for May 1-15.
Thanks to cata for starting the Group Rationality Diary posts, and to commenters for participating!
Next diary: May 16-31
Immediate past diary: April 15-30
Rationality Diaries archive