Yes, more longer the game you can play, it can test your
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.