I think assistants that bounce around a little can take the best of the best of all the head coaches they worked for and package up their own little suite of
To Do's and Don'ts

Head Coach #1 - does these things well
Head coach #2 - does a different set of things well
and so forth

and steal and package all the various good

Than it comes down to executing the concepts and delivering.

College History Professor told me once that taught me and almost taught my son if he went to that college, that whatever you do comes down to

1) Researching information
2) Organizing information
3) Presenting Information