Which answer is consistent with working in small batches? $($Assume that you have $50$ boards to sand and paint.$)$

Sand the boards $10$ at a time, then paint them $10$ at a time. Check quality and deliver.

Sand and paint all the boards and check quality. Put them in bundles of $10$ and deliver.

$($

Sand and paint $10$ boards. Check quality and deliver these. Then move to the next $10,$ and so on$.$

Sand all the boards and check quality. Paint all of them and deliver.