When I worked at a pro lab for a time (early 1990's) we did 4x5 internegs for all transparency print orders regardless of size (35mm, MF) because unless you did your only option was to do an cibachrome print with the transparency. Otherwise to the best of my recollection I do not remember us ever doing 4x5 internegs for negative film regardless of size.
Richard S.
Noting that there has recently been a lot of postings about enlargers, etc., I'm reminded of an experience I had a while back.
Not having done any color enlargements since high school (55 years back, type C perhaps, also dye transfer), I have been sending my 2 1/4 transparencies to a commercial lab for 16X20 and 20X24 enlargements.
With the 20X24 prints I often get back a 4X5 inter-negative or transparency.
The shops say this is necessary for best quality.
I think I know the reason why, but would be interested in comments from folks who know about such things.
DAW