watering can is good, you can water the whole field by only using it 4 times
hoe, axe, hammer is good in spring, when you can clear and till everything using maybe 8 times, so it saves you time, and you cant ALWAYs rely on those spirites, they sometime miss a spot, i dont know why, but it hurts sometime
If you've got enough of them working they shouldn't miss a spot - that should just happen if they run out of time.
I don't need to water though - the sprites do that for me. I can see how the hoe might be useful in Spring, but not the ax and definitely not the hammer...
part of the game i guess, if you want to complete it, just spend ~2 hours in the mine and you'll be fine, so its up to poeple if they want to take on that special tast i did and glad i did, but if i were to do it again, NEVER EVER am i gonna spend that much time doing such a repetitive task