New PMs are expected to ask questions. Heck, if they don't, something is broken. But everytime a new PM comes on board, it is not only impractical but unreasonable to stop the show until they become comfortable enough to understand the "whys" behind decisions.
A lot of the PM/PMM job revolves around personal experience - that "sense" you develop from working with sales, customers and analysts for the space you play in. It would be ideal if new PMs came in with this "sense" fully-formed. But we don't live in an ideal world.
So I ask: how much research do you need? Obviously you need the basics: size the market, assess their options, determine whether or not you are solving a problem that is pervasive, urgent and worth spending money to fix. Add in all of the historical data that you can lay your hands on that demonstrates how they've bought in the past. Layer on what the analysts have to say.
It's a stumper, because while I don't have the time for analysis paralysis, I respect the fact that new blood brings new questions. I'm curious how all of you deal with this problem.