Well, his predecessor, Erik Ten Hag just got sacked from Bayer Leverkusen only after 2 games, so I don't know why Man United is waiting that long
Leverkusen's sporting director said that they felt things were going in the wrong direction, so they decided to act quickly rather than wait till the situation gets much worse. Maybe United should take the same approach. If there's no chemistry between Amorim and players and if there are no clear signs of improvement, maybe it's better to call it a day and let him go. But they know more than we do, so if they think Amorim has a plan and they're satisfied with it and they are willing to wait for the results, they should give him more time.
I'm not sure what's the sentiment towards him among the Man United's fans, I think there are mixed opinions, some want to see him replaced, while others are happy to give him more time.
I'd like to add that before these two coaches arrived at Manchester United, other good coaches came along and still weren't successful. It's clear that management is the main problem. Ronaldo spoke out about it and was fired instead of fixing the problems Ronaldo reported. It's very difficult to manage a club when management doesn't give the coach much freedom, and I believe that's what's happening at Manchester United. The club's owners are probably interfering too much in the coach's work, and it's strange that they refused to sell the entire club.
It's not normal that many players who leave their clubs playing well, when they arrive at Manchester United they start playing a lot as if they had never played well. Something is not right about this, because it's not just a case of just one player, there are many players.