I have been told in no uncertain terms that papers published with your PhD advisor simply Do. Not. Count. when it comes to tenure. Quote: "Publications with your advisor will be crossed off the list."
An assertion that strong makes me insecure about collaborating with any senior researcher. Will these publications also be tossed out? How senior is senior? For instance, suppose I collaborate with junior faculty at another institution who was hired at roughly the same time. Will outcomes from that collaboration be deemed "more significant" than with, say, a full professor from that same institution? And what about the field? Am I "safer" publishing with senior people from a different field, because there will be an easier perception that I am "carrying my weight?" Or should I simply avoid collaboration altogether, and publish exclusively with my own grad students and postdocs? How do the real discussions go, from those who have actually been in the trenches?
Honestly, I would much rather just collaborate with the people I do the best work with. (Isn't that the best thing for the field anyway?) But I am terrified of having years of good work "crossed off the list" because I did not pick the right dance partner.