When is it time to get up

[Clownfish]

I was playing 1/2 on a Crypto site last night and saw that the table was 15/5. I never seem to leave tables to find better games but this was a little too much for me so I actually left the table for another. It started me thinking that I don't do this often enough. I usually just try to rough it out but, obviously there are better fish to fry. How often do you leave a table and what are your bounderies for staying/leaving?