The Saints boss is not happy about the fixture congestion caused, especially for teams that already have so many games.
Southampton play Tottenham tomorrow in the Fourth Round replay, which means their Premier League winter break is delayed.
Hasenhuttl told reporters: "I think you must separate the two things.
"One is about the schedule of the FA Cup with the replays.
"My personal opinion, you know, I'm not a fan of replays because it minimises the chance of small teams to make a big miracle and reach the next round.
"It makes it more difficult because after the draw you have to play a replay.
"The second thing is with the schedule because we all agreed in the summer that we'd have the replay in the winter break.
"Next year we should maybe think about whether it's necessary to make it in this week.
"I think we must see that it doesn't make sense because then you might not have a winter break.
"But, for us, it's maybe not that hard as for the teams who are playing in the Champions League and have three games every week.
"We didn't fight 90 minutes against Tottenham at home to go there with the Under-23s.
"It's a big game for us and we will take it seriously."