Do some plan sponsors tinker with the IRS-preapproved documents?

As service providers get more experience with choices users of IRS-preapproved documents make in using those documents, here’s two questions I’d like to crowd-source:

What percentage of users add an “administrative” provision beyond what’s in the standard documents?

What percentage of users add an arbitration provision?

In my experience service providers offering a mix of 3(16) and 3(21)/402(a) services include the provisions more so than non-fiduciary service providers.

AbsolutelyOkayPossibly, thank you for your help.

Any more observations:

Do employers that are users of a preapproved document add provisions beyond those one may choose in an adoption agreement?