This is not a Q, not a complaint or bug either, really more of an admin anecdote:
Today our scholarship coordinator reported to me that the "Number of Scholarships" and "Number of Scholarships In Process" custom fields was showing wrong counts for all students (like, all zeros).
These are numeric fields on Contact that are the target of two customizable rollups. We model a scholarship as an Opportunity with a record type of Scholarship.
Well, the name of the record type is Scholarship now, but until last month it was "Received Scholarship", when staff and I decided to shorten it to just "Scholarship" (we track both incoming and outgoing money flows so using the words "Received and Disbursed in rectype names seemed helpful, but it turned out that it made the Opp names hard to read due to length).
Well, changing the name of the rectype broke the NPSP customizable rollup filter rule that filtered Opps on rectype = "Received Scholarship". I took a look at the rule and sure enough it said "record type equals" then a blank. So I edited the rule to use the new rectype name "Scholarship", ran a batch rollup, and all was good.
I personally wouldn't even report this as an NPSP "bug" - I mean, how often does anyone change rectype names? Rarely if ever. I think the real moral of this story is that it's in the nature of Salesforce's fantastic customizability that a sysadmin is required to always be around. It's a complicated machine we're flying, and stuff -- happens.