Excellent question!
I throw them in large groups at an area, and then use the contacts list to discover contents of all the asteroids they have landed on. Then i move to the next dozen.
If i find more than 2 painite lots, i have to get busy, or throw a new few out to remember where they are..
but generally after getting no hits on a dozen unique prospector tries, i temporarily disable all power to the prospector collectors[resetting them], move a short ways away, and try again.
Its wasteful, but allows the most information on the rocks i see in my immediate area.. organizing fire groups so that it works for you is your process.
Sometimes i use more cargo, rather than a 7A prospector on the Vette.. the Condas i use all run the formal-normal 5A and 3A.. giving 6 at a time.. which is fine.. but not as good as a 7A, a 5A and a 3A .. which is what.. 14.. thats 36 limpets in three 'spreads'.
Im mining right now.. and i timed how long from first shoot of a laser to a new roid, until all was collected. One minute one second.
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Oo?
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Spike.K