I have done that for builders who had their clients only complain about lippage in specific areas of a floor.
I have done enough to know that it is a marginal practice.
If you flatten the floor in certain areas it is quite noticeable especially to a detailed oriented client.
There have been times when after delipping areas we had to go back and delip the whole floor.
So we never do partial de-lipping jobs for direct customers-its either we delip or we don't.
Anyway for the builder clients what I found works better and makes everyone happy is just knocking down the lips to an acceptable limit.
I try and match the worse areas to the areas the customer hasn't complained about.
I mark off those areas and use the midway point of a tile so I am in between the grout lines.
This way the transition point is less noticeable. I take the toe trippers or lips that will bounce the machine into the air down using genesis or similar electro plated abrasives( on our hands and knees).
Then I run 4- 3 inch copper diamonds (120 grit)(Bulgarian coppers) on a swing machine and just bring the lips done enough to blend in with the existing floor. The downside is it takes time even on a soft stone. Works great on travertines but we do it wet except for the initial Makita work that we do dry with heap vacumms.
The upside side is -it wont pull much fill and it can (in most cases) be followed by a 120 grit resin diamond.
Its a pain in the ass and I only do it for regular commercial clients but it works quite well.
We don't typically have any issues with picture frames on these type of jobs.