best practices for TAGS

[Xavier Noria]

I would basically like to have a workflow for the TAGS file that makes
some assumptions, and thanks to them it works out of the box and it is
always in sync.

For example, define the current tags file as the first one you find
from the current directory up the hierarchy, nil if none found.

I'd like to define my own version of find-tag that looks for the
current tags file as defined above.

If the tags file is outdated, I'd like to run some shell command
automatically and revisit it, then do the find-tag.

No prompts whatsoever. If I find myself in a situation where the
conventions do not hold, I'll resort to the builtin functions.

You see, I'd like that find-tag and friends do automatically what
makes sense in 99% of my projects and be always in sync without my
intervention.

Does anybody work use a worflow like that?