Don't be overwhelmed. It seems like a lot at first, but once you get all the settings right - you're done! Then it's just a matter of monitoring and slight tweaking where needed.

All you have to do is look at the basic biology of the ball python to know heating the enclosure from the side does nothing for them. That's not how it works for them in their natural habitats and it's illogical in captive habitats. They will search out a ground hot spot after a meal because their instinct dictates this must be done to digest properly. They can't get their underside curled up on the side of the tank, and a UTH doesn't radiate enough heat to do anything for your ambient air. So it's just pointless for this species. As Zinc mentioned, it is done for other species, just not for balls because that's not how they work.

Your friend's setup may work for him. But who knows what other variables are at play? What his home temps are like, what environmental circumstances may allow his snakes to get along fine kept in inadvisable ways.

Do you want your snake's environment to just work (and that's a totally subjective term), or do you want it to be ideal?

If you want his habitat to be optimal - and who wouldn't? - then please listen to what you're being told here. Make a shopping list, hit up Amazon, do all the things, and watch your new pet thrive.