I am working on 'a' collection that four generations of family contributed to. If there was such a thing as 'too much', then one might say I could be in big trouble, particularly since, 14 months ago, I knew nothing about philately.
I agree with Jenny2U, it is the variety, that has held my interest, and rapt attention.
Most of my time has been spent on the US Classics, which is a 'postmark and cancel collection'. Once I got into the 20th century, I found the 'series' part of the collection. Sometimes I take a break from all the red Georges and blue Bens of the classics, and work on the Liberty, Great Americans, Prominent Americans, or Transportation collections. Or, I skip to 'the end' working towards rescuing the last of the stamps that will bring me into the 21st century. (I'm up to 1994, so I'm getting there).
I can't wait to get to the foreign collection.
It's been an overwhelming, and daunting task, to put the accumulation into some sort of order, and making it a 'collection', or 'sub-collections', but I've never considered it 'too much', other than perhaps, 'too much fun', as I've taken great joy in the things I've learned.
Since you say you are a 'returning collector',
I say 'Welcome back!'

and, if your heart wants to start a collection on engravers, go for it. May it bring you great joy and new discoveries.