You can increase Huntsmen work time many more hours than with upgrades alone by crafting “feasts” in your Summer Kitchen and using them to increase worktime in your huntsmen’s tent. Feed your Huntsmen FIRST. Then Increase the worktime. This tent is upgraded all the way.
NOTE: Before you increase your work time, make sure you have the time in “Real Life” so you don’t waste resources!
Max time would be 6 hours and 20 minutes.
Using a “FEAST” I increased work time by 2 hours.
Repeatedly increase worktimes!