Odds movement isn't just about money coming in, but also relates to pre & current events. For example, in the middle of a match, if the home or away team gets a red card, it will cause the odds to change drastically. I usually only observe the pre-match section, 2 days before the match starts I will look at the odds, then I will do a second check 5 hours before the match starts.
I realize that what I do doesn't have a strong impact on winning, but at least it increases my slip winning chances.
There is a certain correlation between the money coming in for Team A to win and Team B getting a red card, isn't there?

As for how useful it is to monitor changes in quotes, yes, it is difficult to profit from this (unless, of course, you trade quotes), there is a certain paradox in this - no matter what the quotes are and no matter how much they differ from those of an hour or a day ago, they are always fair (this doesn't give you any advantage, it stays with the bookmaker).