The judge won't be amused if the police say it took them 45 minutes to write a speeding ticket.
I've definitely been detained for what seemed to me an acceptable amount of time for a traffic stop, but who's to say the cop can't come up with myriad reasons it had to take that long? Is 35 minutes too long? Is 38 minutes? Who's keeping time, and who's word is taken as truth?
The increased use of car and body cameras makes this particular abuse harder to get away with. A request to search denied followed by a call for a dog, followed by unusual delays recorded on dashcam leads to a challenge even the most overworked public defender would raise.
If its a black man in a poor part of town driving a cheap car your success rate in getting away with it will be 100%.
I'm not saying it never happens, but the legal risk is too high for most cops to do it often. They may try to get you to think they will, but it's usually a bluff.