I wouldn't think that 5" deep would be common. Mine are old but i think they're around 3" deep.

take a look on HD or Lowe's just to see how deep theirs run.

Two of our Robern medicine cabinets are 3.5" or 4" deep. (we used a 6" deep one in the MB). We are very happy with them.

Have you looked at Sidler? We've just ordered a cabinet from this manufacturer. Wasn't cheap though! I think they have pretty slim depths that are less than 5". Their website has all the specs for each one under 'product lines'

Here is a link that might be useful: Sidler

I believe all of Kohler's cabinets are that deep, hence my problem.
cat mom, which Robern cabinets did you use ?
Thanks,
Salbwil

The 3.75" deep cab we used is linked below ("PLM" series). The one in our hall bathroom is 19.25" x 30" (we used a narrower one in the guest bathroom, and the deeper version that I mentioned in my first post--6" deep from the "M" series, was used in the MB).

There are different sizes/dimensions available in the different series.

Here is a link that might be useful: Robern medicine cabinet

Modern studs are only 3.5 inches deep.

Anything more than that has to be from the cabinet protruding into the room.