[RealJames]

I've taught in Kenya, Korea, for foreign university students in Canada, and in Japan.
Surprisingly little of the experience from any one of the places could be carried over to the others... well Japan and Korea a tad alike, but that's an overstatement.
I would have sometimes been better off with no experience rather than trying to adapt what I thought I knew.

Teaching in Japan, honestly, is a walk in the park compared to other places. The grammar base is so strong it's just giving chances to speak and a better teacher notices repeated mistakes and their underlying common misconception then drills that form a little.
This of course can't be applied so easily to someone with a weaker grammar level than spoken.

I recently conducted about 30 interviews because I'm hiring a 2nd teacher at my school. all but 3 of them were absolute shit. there are so many absolute shit teachers out there who aren't teachers at all, just native English backpackers or no-lifes hoping to get laid in Japan

Edit;

about how easily lessons are absorbed.
I've tried various teaching methodologies, and honestly the retention depends far far more on motivation and time spent exposed and in practice than teaching system or even age do.
I was shocked last year when one of my best students, by best I mean advanced the fastest, was 75 years old! (Learning English to hit on boys while traveling lol)

edit2;
@robinmask; the most difficult part is to keep caring about individual student's needs when you are #2000 and your schedule is filling up a lot and it starts to feel too much like a job than a service to another human... Thank GOD I no longer work at a school that made me feel that way!