I've been in this position as far as being a vendor, I have a shop owner perspective from life experiences.
Think of this as mandatory overtime, because thwere is no way around it. You have to do it along with all your regular duties that are day to day chores. You have to keep money coming in to support yourself, your business, your family, and obligations.
So we've established the owner has a set schedule to keep his head above water financially. And the boss, in this case the warranty claim, is wanting the overtime to commence ASAP. Adding in an extra 10-15 hours a week of overtime is something most people can identify with. The averaage worker gets 1.5 times his regular hourly pay, so there is a reward for you to take time away from your regular weekly duties, or pleasure time. It's called sacrifice, but the regular hourly employee is monetarily compensated. The shop owner on the other hand has to put the time in, but he was paid for the original work months ago. It's not only not bringing any money to the bottom line, it's costing him overhead besides.
How many here want to be put in this situation? These are some of the joys of owning your own business. When everything goes as planned you make money, and only answer to yourself. When things go wrong, you no longer are the boss, the customer has become your boss, and he wants it done yesterday. All the people that lament why good reliable engine shop owners retire, and no one wants to fill the voids left in the hobby when these people retire can see much clearer when you look at situations from someone else's viewpoint.
Tread carefully when you think about trying to push your warranty work through on your schedule, as opposd to his schedule.
How long? As long as it takes.
My
, take it for what it's worth.