Prospector limpets don't add much value once you get good at mining -- you can tell quickly what is in an asteroid by mining on it once or twice and it is pretty easy to know when the asteroid has been "depleted".
Agree it's easy to determine depleted, and choice to use up to you. Also agree can learn to tell quickly and execute the short mining blast, check chunks, keep mining or move on step all in one quick smooth action.
Liking or disliking prospectors is an opinion. Not caring to use them is also your right and opinion. But simply fact that no matter how good at mining you are, prospectors will add value - it is simple logistics and incorrect to dismiss prospectors as "don't add much value once you get good at mining"
Let's say for sake of argument you are so good, so fast, the entire step to micro-second blast few chunks off asteroid, target chunks, and see what kind they are to determine whether it is worth mining the rock or not takes all of 0.00001 seconds. This is not realistic of course, but again - let us say for sake of argument that literally you take ZERO time to do this check.
Logistical block #1 - mining lasers are short range, very short range. You can not check an asteroid without being in mining laser range. Agree?
Logistical block #2 - moving your ship to within mining laser range to check the next asteroid takes X interval of time ; whether you move fast or slow, this is still an X interval
Logistical block #3 - no matter how many collectors you carry, they do not instantly pick up every single ore chunk, nor do they pick them all up in one pass. There is an interval of time where your ship must sit there waiting for collectors to come back. During this time, good miners manage their refinery.
Prospector advantage - while your ship is motionless waiting for collectors at current rock, you can skip the time to move ship to mining laser range to check an asteroid by simply firing off a prospector, which closes the distance between you and the asteroid much faster than your ship thrusters can.
Whether you want this additional advantage is totally up to you. But you can't rationalize away that prospectors save you that X interval of time to move ship within mining laser range even if the step to laser, target, and check chunks is instantaneous as waived for sake of this argument.
but reality is you would save both the X interval of movement time, the Y interval of blast/target/check chunks time, and with multiple prospectors, have scouted out the highest yield of the top metal asteroids. When you check with mining lasers and you see a few chunks of palladium - you will naturally stop and mine that asteroid. Bu you may be mining only a low percentage palladium asteroid, whereas with multiple prospectors,you can cherry pick only the highest yield ones - with zero time spent to get that intel.