Tips on being ruthless/efficient with research?

This may sound bizarre for a lot of people here with IBD analyst background, but it’s the only venue I know worth asking… So here it goes.

I am doing a “pro-bono”/trial buy-side research for a hedge-fund friend, with not-so-hidden agenda of proving that I’m worth giving a shot as an analyst. I have breezed through building the model (got MBA in finance and CFA l.2) and recognizing the big picture, but now am stuck with the actual analytical part where thinking is required – coming up with defensible assumption ranges. The problem is abundance of online information, coupled with my perfectionism… There always seems to appear another angle of the issue worth investigating, which brings another 10-15 papers/reports, and so on…

For a sell-side work, it wouldn’t be much of an issue, I’d just settle on combination of reputable enough sources that collectively maximize valuation. But for buy-side I feel compelled to find the actual truth, and that creates this never-ending scope creep.

I am familiar with time/project management concepts and am keeping the project structured, with milestones and deadlines. But, in the absence of employer pressure (and the presence of full-time job) this research is moving so frustratingly slowly and makes me feel exhausted and guilty for still not having accomplished much. To preempt a possible explanation, it doesn’t mean that I’m unfit for buy-side analyst du-ty, it just means I’m doing something wrong… :-) (haven’t done this before at this level)

Any advice on how to deal with this? If you do buy-side research professionally, how do you draw a line of “good/credible enough” and move to the next piece? Is it some-thing that can only be learned during the 2 years of IBD analyst pressure cooker? Or is it the PM pressure that creates enough momentum to crush through indecision and confusion?

I realize everyone here is busy; any contribution will be appreciated.