3-4 chains per cassette, 3-4 cassettes per set of chainrings/crankset. Check your chains at 2,500 kms with a chain checking tool and rely on that. Replace when 0.75 or more is indicated.
For old school 6-7 speeds or Tourney, you may get more life out of everything, which may be the reason for all the hand wringing over a $15 cassette earlier in the thread?
On my commuter I get 3 chains to a Sunrace cassette (with light skipping on chain 3 until it wears in a bit) and 4 chains to a Shimano cassette.
Chains are cheaper than cassettes, which are cheaper than cranksets. Leaving chains on for too long will wear out both cassettes and cranksets.
Last edited by PDKL45; 07-22-22 at 12:56 AM.