Can you ever stop?

My TNG tree currently stands at 1279 individuals with 236 families and 153 unique surnames.  My tree is barely a branch compared to others that I know of but a lot of hard work has gone into it.  I’ve spent countless hours in front of a computer screen piecing together each of the families, not to mention the time taken actually filling in the various data fields…

My tree mostly consists of the traceable direct ancestors and their siblings so far, however, with 1279 individuals following each person from birth to death seems like quite a challenge at the moment.  This task not only involves adding spouses and children of my direct ancestor’s siblings but includes events (eg wills, census, and occupations) and addresses of each individual within the tree.  Where do you stop?  Is there a point where you say “I’m not researching that family”?

My quandary is, do I continue researching every name on my tree and end up with hundreds, if not thousands of people only related to my ancestors by marriage?
There is always the opportunity to research them and theirs at later dates.

Would you stick to blood relatives first?  Then move on to married in relatives?  Or do them all at once?