My favorite myth is that pinching your thumb to your 1st, 2nd, 3rd, fingers and poking the fleshy bit of your palm can be used to cook a steak.
I've seen many seasoned chefs try to teach juniors this way (and someone tried to teach me this also).. Yes, it is a good metaphor that as a steak cooks it goes from squishy to stiff to hard.. but to literally compare "touch thumb to ring finger is med-well".. well that's just bunk. I've seen junior cooks standing over the broiler poking their palm, then poking the steak, then poking their palm...
LOL...i've had guys standing there doing the same thing over the grill.
The feel test has always been my meat tester. I don't use my finger anymore, just tongs. Been cooking meat a long time, i'm pretty confident in my temps.
All the kids use the feel test now that i have working there. I've never had anyone probe a steak while i've been there.