MaxxAir II Vent Covers - Installation

Hello--
I had 4 MaxAirII vent covers installed about 9 months ago by a VERY reputable local RV repair shop. Shop has been in business since 1958. They've done work for me over the last 20 years and it has always been top notch work with fair prices.

At the same time as vent cover install, I also had the entire roof washed with conditioner and resealed all roof protrusions. Shop used Dicor lap sealant for all roof resealing. Roof is 12 years old with many black dots all over where white has rubbed off. Shop said roof would need to be completely coated in the next 1-2 years as more black spots appear indicating white material is degrading which is normal for an EPDM roof.

After speaking with them about the vent install, I asked how my vents were installed. He explained that the mounting brackets are screwed directly to roof. I asked why would additional holes be added to roof making for potential leaks. He said the screw holes are all sealed with same Dicor lap sealant used to reseal all vents/holes. They have always installed them this way with zero problems (over 30 years). He said not to worry about leaks, just be sure to inspect roof 1-2 times per year and add lap sealant to areas as needed.

I mentioned that I had installed them personally in the past, to sides of the aluminum framed vent to avoid holes in the roof. He said that was another way to install but for shop to install that way would increase labor costs to customer (perhaps twice the labor hours).

Is screwing to roof a BAD way to install these vent covers? Nothing to do about it now since there were already installed.

I'm a worry-wart and this kind of stuff lingers in my mind.:?

Thanks!