Has anyone else reliably used frame count to time runs where that precision was needed?

Situation is that I mod/run Mercs Genesis. In the real world the Genny's max frame rate is tied to 59.92274 but emulation puts it at much closer to 60 with occasional drops to 59. On past occasions where I've had a very obvious time (in the middle of a second for example), I've found that doing (Frame count/60) + 1 second has always matched the real timing for full runs.

What I would love to know is whether anyone else has reliably used such a method or whether it is flawed. My stopwatch timing was synced from the first frame, but I ended manually with reaction time in play, which showed 13:39.03. If I do F/60+1 I get 13:38.73, and if I do F/59.92274 I get 13:38.75, but since this is supremely close I just want to be as sure as I can that I'm not making a mistake.

I use framecounting and it works, but admittedly my experience is only with integer fps values and decent videos which are intact. Especially when looking at videos on third-party sites, you''ll have to be careful.

This is a great website to re-time runs frame by frame (if they're on youtube): https://mattbraddock.com/yt-frame-timer/

My question was answered on r/speedrun by someone who told me that Bizhawk's frame counter is based on vsync, and that it is correct to divide frame time (I am talking about game frame-rate as opposed to video frames) by 59.92274 for NTSC Genesis runs.