Assume that one has a skill (assume, programming) and is one of the very few in the department to have it. The other students need a bit of this skill for their projects and you help out when you can.
Where do you set the limit for how much effort/time you spend on helping others this way?
- You get insight into other students' work.
- It's a welcome break from our own research
- Maybe earns you a second/third author for setting up the experiment
- Networking !
- Effort/Time spent
- You don't necessarily improve your skills (For instance, coding in Python for someone else doesn't augment my Python skills by much. What I do might be really routine)
- You tend to have a soft commitment towards that project. For instance, if I start working on it as a favour, it doesn't really come off well if I leave 'em midway.
EDIT: I do enjoy the work so long as it is at least a little challenging. I often get really n00bish questions and that is when I start reconsidering my stance on helping people.