How Many Projects Is Too Many?

It's a rhetorical question. Please don't give me advice! I currently have four books on the go ... 3 non fiction, 1 fiction; 7 articles; 2 contracted freelance pieces; 2 classes to prepare; and timetables looming for July too big to mention. I have three possible consultancy pieces I am in the running for ... I also have a life (like 2 baby budgies just born in our aviary and a daughter going for her license needing extra lessons for example) ... So I ask (rhetorically again!)...

"How many projects is too many?"

Well I haven't hit the barrier yet.
This feels damn good!