Since version 8 doesn't have script triggers, you'd have to limit layout navigation strictly to scripts performed by clicking buttons or by selecting them from the scripts menu.
If that can be set up, just include steps in each such script that logs the user (or account) name and layout name in the log table.
Something like this can be put in a single script and then called by every script that changes layouts:
Set Variable [$LayoutName; Value: Get ( LayoutName ) ]
Go To Layout [LayoutLogger]
Set Field [ LayoutLog::UserName ; Get ( UserName ) ] //or use get (account name)
Go To Layout [Original Layout]
The challenge here, is that you'd also need to go through every single script that might have the go to layout or Go To Related Records script steps and insert a call to this script in every case where you find those script steps.
Thanks Phil! You confirmed some of my thoughts and got me past my mental block for the next step in moving forward. I'm pretty sure the script steps you listed will do the trick!
Don't know what you can still get for v8, but with filemaker 10 and 11, you can use filemaker advanced to generate a database design report that can help you analyze what parts of an older system might not be needed anymore. There are also third party applications that take the DDR and provide enhanced analyses that would likely be very useful for this.
I put my old converted from 5.5 tables on a "field diet"--deleting dozens of no longer used fields by doing systematic text searches of each field name in the DDR. If I couldn't find it anywhere but in the field definition, it was a good candidate for removal.