There are plenty of guys who don't need cialis/viagra on TRT.
In my opinion, requiring a PDE5 inhibitor would indicate that you are not dialed in unless there are other underlying issues that would require the use of a PDE5 inhibitor like vascular issues.
It drives me crazy when guys say "I have my TRT dose dialed in" but require Cialis for an erection and 5 other medications or supplements to deal with the effects of their dose.
It's also misleading, as people rarely share their entire protocol when offering advice or what works for them unless they're asked directly. They might say "I'm doing great on 75mg twice a week" but neglect to share that they need cialis just to get an erection, aromatase inhibitor/hcg use which influences protocols, other prescription medications, HGH, peptides, etc. There is a big difference between 150mg of test, and 150 mg of test with daily cialis, .25mg anastrozole twice a week, 250iu hcg every other day, etc.
Like I said, this is without other conditions that would require other medical interventions. But if the dose itself is causing ED, certain side effects, etc, the dose is most likely wrong for that person. Its usually the high dose guys, but I've seen it across the board.
All that being said, if you tolerate/enjoy/benefit from Cialis, there's nothing wrong with using it.