In my case, I would say there was a 90% or more improvement using what would probably be considered a 75 mile range outdoor antenna to lock in on a tower 35 miles away over flat ground in South Texas as compared to a twin "bow-tie" antenna mounted to the rear ladder of my RV and about 13' above the ground. The directional antenna that came on the RV was even worse. There was an airport in the direct line of sight between me and the transmitting tower. It is possible that air traffic caused me to see the dropouts you describe, as I suffered the same thing. I never hit 100 on any channel. The tuner has to have some type of AGC, automatic gain control, and if you hit 100 and things work like they did back in the 60's, something would have to react to keep the signal from overloading. BUT, I think the main problem is just cheap tuners.
FYI, you can go to antennaweb.org and get a list of channels and it will tell you the actual channel number and the indicated channel number you see on your tv, so you will know if a channel is actually on VHF or UHF. In my case, Channel 4 is actually broadcasting on something like UHF Channel 23. And, in the near future, there will be another round of channel changes. Apparently some of the UHF band is being reallocated to 5G and other uses and stations using those channels will move to another UHF channel. And, maybe, some of the few remaining VHF channels will move to UHF.