Let me first say that, I'm a challenge chaser. So when I found all those goals available to achieve in RB3, I was quite thrilled! I didn't actually start ACTIVELY getting the goals until about the end of December...although I had a nice bit of them completed before then, just playing through the songs on guitar and such. However, I feel that I have now hit a brick wall. I'm afraid that I won't be achieving every single goal that's available. I've played through all the instruments (except for Pro guitar/bass...waiting for the Squier) and am very close to Perfectionist on all of them (regular Vocals, I am Perfectionist on), but...I don't know that I will actually complete the rest of the goals.
For example, 5*-ing songs on Expert on the various instruments...unless I invest a lot of time with certain songs, which I'm not entirely sure I can/want to do, I probably will not 5* all the on-disc songs. The Harmony goals? I maybe know of one other singer that I could get the Double Awesome challenges done on SOME of the songs (if she doesn't know the song, I doubt she's going to sing it), but I don't know if I know 2 people that could sing some of those 3-part harmony things, and once again, if it's a song they don't know, I doubt it will even be attempted.
If you are not a Completionist, what are your "brick wall" stories? How many goals do you have done? If you are Completionist, how much time did you have to invest?