Do longer games better your chances of honing chess skills? What do you say about it?

I find that if you're in a sequence that you're realizing is a trap, and the pressure on you is building. Or you've blundered, or worse, you deservedly are about to get crushed—its a traumatic experience where the ideational nature or principles of the position are more readily gleaned.
Yes, more longer the game you can play, it can test your concentration, visualization and memory power.

When I initially started playing Chess, I was always excited to play blitz Chess. I kept playing and finally I couldn't improve my Chess as I didn't improve what was needed.

Recently I played with a time control of 1 hour in my debut FIDE tournament, I took the most time for my moves against my opponent. All 9 players I met in the field were having Class C rating but then they had the basics right. I could win against 6 and drew with one while losing the remaining two because of minor blunders. Luckily, I could open my FIDE rating in my very first tournament, though the rating is not much to be proud of. It set a platform for me to concentrate more on longer games and less on blitz.