[Suicide Junkie]

Personally, I always use the highest possible value.

My settings.txt uses Max = 100,000
but the game cuts that down to 5000.

For me, that's 5000 units in space and 5000 units in one sector.

But yes, if you include enough sweepers to clear the maximum size minefield, you will never run into trouble.
But note that the maximum size is "max per sector" PLUS "Number launched at once" MINUS one.
If the player used a baseship filled with mine launch bays, or even a Starbase filled with launch bays, that number could be very high indeed.