I would love to have a way to report on all my custom fields and filter by FORM. At this point I am unable to get a list of fields that are not being used in any form.
I go right to custom forms in setup and use filters there to see what forms use what fields ....and I just now added a column for "custom field" ---trying to see how you'd see how many times there are used. I have a report that shows how many times a "report" was viewed and by whom....maybe that one could work here too.
if I have time I'm going to try and integrate the two....if anyone else figures out I'd like to know also.
the report one is great because if nobody is viewing one - it may as well be deleted! (we have a lot like that)