They are pretty much a waste of time. We do something kind of similar to the old school 60 second drill, but it is all quick stops and starts between the goal line and the center line. Way more effective to condition for game situations, and the stops/starts are actually useful for game situations. Suicides are a complete waste of time because you can accomplish the exact same conditioning doing shuttle runs....OFF the ice.
Most practices, I just try and keep the kids moving the entire practice, and moving at full speed, with a lot of edge work involved. After warming up, most of that time is with pucks, as well.
Suicides and no-puck drills are antiquated garbage. I really didn't learn to be a very good puck handler until 13-14, because my coaches up until that point were idiots that gave us pucks like 20% of the time... Even then, I have improved my stick handling more in my late 20s and 30s than I ever did in youth hockey, because I spent an hour a week at rat hockey by myself for several months straight just stick handling and shooting.
I am grateful that coaching has moved away from the old school crap I grew up with, because it just wasn't very effective. The coaches could teach you the mental part of the game, and systems/responsibility, but they did a piss poor job of actual skill development.