Good background to have David!

The job I just started on Friday is a seasonal "cabin" (not log) that is in good repair but typical metal roof we see in the mountains
here.
The folks hired a local handyman last year to seal where they saw bats post fall last year when they assumed the bats were gone.
He actually came by when I went to inspect and noted to me in front of them that the "darn bats pulled the material out" that he
had installed.
The day I inspected the clouds burst and lightning along with it and so the high roof wasn't inspected, just bid based on the logical
issues we always see in any of these areas.
When I went to do the work on Friday I ascended the 32' ladder to reach this ridge he had sealed and what do I see at the top? That
every screw within 2' of the end of this ridge point have all loosened to the point where the 1 1/2" roofing screws are all showing completely
head to tip. His roofing foam inserts that were caulked in were literally standing on end in the space with no sign of any damage from chewing
just simply lifted out when the roof lifted...
I see this a lot and as I believe Paul A. mentioned awhile back on here about how many roofs they sold folks a side job of screwing the roofing down
with larger diameter roofing screws to reaffix it, I see tons of opportunity for this and with the bat exclusion and anchoring materials we are always trying to make sure we anchor anything we do where the roof will have to completely blow off before we might lose our seal.
Of course as we all know there are things that should be outside your warranty that can and do regularly happen. Had a home where they noted bats had returned and as we turned the corner of the structure 4 pieces of cedar siding were completely gone from winter winds and storms leaving a nice 2x4' gap for bats to enter, nothing to do with exclusion materials.
Anyway, pays to think of these things no matter what material you are using, when selling exclusion services...
Justin