I have only had one mounting plate come loose across six guns and a HUGE amount of rounds since 2016. I can't even begin to tell you how many rounds i've put through these pistols in that time frame. Probably upwards of 150K.
The only plate that had issues was the C&H Holosun 509 plate.
My Forward Control plates and C&H plates for my SRO's have all remained tight.
I will note that up until last year, I was using vibratite VC3 on everything with a solid degreasing routine prior to install. I would degrease the screws and let them sit. I would apply the vibratite to the screws, allowing them to sit for twenty minutes. I would degrease the plate, slide and let that sit. I would then install the screws into the plate according to the manufacturers specs.
I would then install my optic following the same pattern regarding degreasing, VC3 application and then torque to spec. The pistol would then SIT for at least twenty four hours.
As stated, I only ever had the one issue with the 509 plate and the 509 itself.
I have since switched to loctite 248 and have had zero issues since then but i've only been running that compound for about a year now.
As others have stated, there certainly is a way to semi permanently mount these plates. I find the biggest issue with the whole setup is that when you're running a plate, preventative maintenance is harder because you have to remove the optic to check your plate's screws. Given that I generally replace batteries once a year and check everything, this is more of an annoyance than a real issue.