You can speed up your migration to lightning and understand if you need to spend time optimizing buttons and other components by checking what profiles (and how many users) are actually assigned to a given page layout.
- Checking page layout assignments
- Reporting on page layout assignments
Checking page layout assignments
In the Org Model, select Page Layouts listed under an Object. Click on the fingerprint icon in the right panel (Page layout access by profile) and you will see a list of profiles assigned to that page layout.
If you roll-over the profile in the list you will be able to see more information about it. At the top of the panel, you can see the total sum of all active users assigned to that page layout.
Reporting on page layout assignments
You can do a quick analysis of page layout assignments for an object by using the report feature.
First, select the object you want to investigate, right-click on it and make it the "root node". That will limit the scope of the org model tree to just that object.
Then, select the report icon in the upper-right corner of the screen. Choose an option to run a new report and select "Page layout: assignments" from the available list.
The report will bring back the list of page layouts for that object (with label & API names for both the layout & the parent object) with each profile assigned to any of the listed page layouts as a column.
You will be able to see which profiles are assigned to which page layouts. If you cannot see a specific profile in the columns it means that it is not assigned to any of the page layouts