Waxing by hand is fine because its not too much work unless you're doing several cars at once.
Cleaning/polishing on the other hand is exhausting and a machine helps.

U mean after apply wax, the process of wiping (buffing) it off?
If you applied too much wax or applied too thick, you may experience difficulty to buff off the wax. Apply thin layer of wax is enough. Save wax, save cost and save your buffing time 

A little bit strength is enough to layer the wax, as long as you can get every area cover evenly with the product. Yes, I do own machine, but when it comes to wax application, I usually apply wax by hand 

Enjoy detailing ! BTW, what kind of wax are you using? Meguiars wax?