I noticed that sometimes WTA players waste challenges prematurely, sometimes even foolishly after the first few games. Some players ask for challenge and the ball is like 15 centimetres out every time as well. :SNE: :silly: I mean they have someone in their box who can even by facial expression or simple gesture suggest that it makes no sense, let alone crowd.
And there are others who ask for challenge already after returning the ball to the other side in neutral position thinking there was out instead of going on with a rally. :tape: Then they often proceed to lose this point, sometimes very crucial one. Some memorable instances: Kvitova - Janković match at Wimbledon late in the match few years ago. Linette last week vs Babos in 2nd set in Taipei (Linette gave away her own service game by losing BP in this suicidal way).
I remember Venus Williams not taking challenges when she really should or could have in the past on the other side too but when she takes challenge she's usually correct.
Ostapenko is really bad when it comes to challenges on the other hand.
I suspect that some of these, hopeless challenges are used to throw off your opponent, to catch your breath, get a break ... more to do with this sneaky purpose thinking about the next points than to get more favorable call.