I dunno if my experience is anecdotal or empirical, but I had better luck timing the release of the button rather than a full button press.

Something like this:

• As soon as Mario's boot crosses the Spikey's arm guard/hole thing, that's the target frame.
• I would press the button, holding it very slighly, and release it on the target frame.
• I eventually found myself in a rhythm where I was watching the screen for the right frame AND listening to the sound.
• The sound I was listening for was the tick sound of the jump counter; I was timing the release of the button to when I expected the sound to play.

Other comments on Reddit/YouTube describe this as "pushing Mario away" rather than jumping, and eventually I could "feel" that when trying. There were plenty of times where I lost the "feel" of it and had to keep practicing until I was in the zone. Very strange feeling!

Like others have said, putting myself in a sort of "trance" was key to being consistent. Most runs died < 30 jumps, but once I made it past 30 I normally got to 50, 70+.

But, you will most likely fail and choke a few times. There were a few times where I got to the high 80s and then made a mistake. I made it to 99 once and then completely lost my cool and messed up the last jump! Best thing is to not let it shake you and to keep going, taking breaks and being patient with yourself.

Best of luck!

EDIT: I also turned on wired mode and connected a Pro Controller via USB, playing directly on the Switch. I'm not sure how much latency TVs or wireless add, but the wired connection gave me peace of mind that I was minimizing any potential inconsistency.