Crevasses are just as much a problem in the spring as they are in winter. The general rule is that you should rope up and be ready to deal with crevasse rescue any time you are on a glacier.

In my one extensive glacier experience, we were continually roped (three to a rope) and did not get together when we were taking breaks. That was a June trip on Denali.

Lots of stories about what happened when you violated the principle....