Excessive and unnecessary appeals happen all the time and umpires do have complete control over it as they have the right to penalize players or captains, given they have been warned once.
Also when the captains do take review it doesn't take much time as they have only 15 secs to take a DRS call, problems come with the 3rd umpire cause sometimes in pressure moments they even take 2-3 mins.
This is a good video on umpire's call
https://www.youtube.com/watch?v=7MfLv9hqYXMMy concern is that sometimes the momentum is lot when the third umpire spends 2-3 minutes to take the decision. For the viewers who are closely following the match, the flow will be lost. But also, excessive appealing from the part of the players is another issue. I agree that the umpires should be given more powers to deal with it. But in the end, none of us want inaccurate decisions from the umpires to be retained. Overall, the implementation of the DRS has worked wonders in international cricket.
My experience is that I have seen a certain thing happen multiple times, which is that the bowling team often takes a review that is not that close.
However, they take the reviews so that there is a break in play and they can break the concentration of the batsmen who are playing in the middle at the time when the review is being taken. Often we can observe the batting team losing wickets after a break because it causes a sudden lapse in concentration on the part of the batsman in the middle.
There is nothing wrong with this system at all and I am not saying that it is a bad one. I am only trying to say that players who are willing to exploit anything for their own advantage are obviously going to take any chance they can get in order to gain an advantage over their opponents.