Or in that moment you realize demand for your service exceeds supply and the correct response is to raise your rates until you have a reasonable workload. If they won’t pay $5k+ monthly retainer for someone who knows how to build their system, surely they have a cheaper alternative. Meanwhile the clients with budgets you really want to work for are happy to pay your fees because they’re cheaper than your comparable salary. If you’re selling a monthly retainer and hit that collision you describe, you’re in a fantastic position to negotiate rates. Better to be on a use it or lose it commitment than accruing unspent hours, otherwise yeah you can get screwed.