Well, it depends (e.g. your hardware, ...)

Helping the team (e.g. making publicity with that) vs. self-interest:

• e.g. when a Gridcoin challenge takes place, people have to decide if they should stop crunching their current projects which give them x GRC, while crunching a new project will give them less (since you have to build up RAC there, ...)
• one of the motivators, besides marketing, can be: !projectrain

Until Sep9/10 we'll have 3 team challenges in parallel.

We could also make a UNIVERSE@home challenge for the future