Yes. Hire it out :-)

It depends a lot on the type of soils you have. When hand digging, sharpen your shovel and buy a decent railroad pick. It's amazing how much dirt you can move by hand with good tools. On the other hand it's very easy to learn to use a small excavator if you can find a rental place willing to deliver one to you. My neighbor installed a geothermal system with no prior experience.

One thing that almost always helps (in addition to sharpening the shovel) is sprinkling good the day before.

I bought a little Mantis tiller. My soil is very hard clay and impossible to dig where it's not been amended. The tiller is a workhorse and will break it up so I can shovel it...then I till the next layer etc. We call it the Barbie tiller, but it's tough.