You have discovered the difference between blitz and "regular" chess. When your opponents have more time to think they will more often find unexpected good moves. Then you need to spend time re-evaluating the position, and you become more cautious, spending more time checking more possibilities. One solution might be to play even longer time controls, making the time spent on difficult decisions less of a factor.
And remember, all those brilliant blitz games you see the top GMs play result from years of study mastering all aspects of chess play, and a repertoire of a few opening variations they have studied very deeply and thoroughly to minimize thinking time.
Yeah, I had that problem too haha
The one with correspondence games meaning I could calculate forever.
In the past I also solved untimed puzzles a lot... which also contributed to the problem. These days I don't really play chess anymore, but I can relate to what you're saying.