If you use synthetic grease it's a one time deal. You'll change your oil, filter, and fuel filter again before you will have to change out your synthetic grease in your Kitchenaid mixer. It's really not all that bad. If you're doing all that with your vehicle it's a pretty simple fix on your mixer. There's ways to cut down on time but I'm keeping it simple and not saying it can't be done in 1-1.5 hours. It's going to take time as it's your first time.
I also understand if you want to buy a mixer every so often. It's not for all. I'd run out of $20 mixers if people didn't go out and buy new ones! It's more of a recommendation for preventive maintenance. Just like changing your oil and fuel filter on your truck. (It should be done but I've had a buddy drive his old Honda for years without ever changing his oil)
Kitchenaid used to be owned by Hobart. They were bought by Whirlpool in the early 90's. Hobart and the first couple years of Whirlpool used all steel gearing with a stout motor. Whirlpool eventually switched over to a smaller motor and nylon gearing. (I believe the Professional Series still has steel gearing.) I've probably greased 6+ Kitchenaid Hobart's over the years. I could only imagine how many been scrapped over the years thinking they were broken. Hard to beat an older Hobart Kitchenaid mixer. Most of them just need some new grease and they're back up and running.