It is ABSOLUTELY better to focus one one/two things rather than trying to everything, especially if you have limited resources (that includes experience). You can check out Karthik's latest seminar on effective FIRST strategies:
https://www.youtube.com/watch?v=sJOfH-lomEQ
As he says, a jack of all trades is master of none, and it is always better to do a few things at a "10" level than to do a bunch of things at a "5" level. Most alliance captains want robots that find a niche and do that really well, so they can build a good, well rounded alliance.