TNT in Town

I would say you would need between 20 and 25 Shovels in addition to the enchanted one. I've worked with someone to clear a Residence not too long ago and we were using Unbreaking III Efficiency V shovels. I recall averaging about three levels of Dirt before I got close to breaking the Shovel. I usually would stop quite a ways before it was used up for safety so I may have been able to do better. Then I would go to get 29 levels and repair it using a regular Diamond Shovel.

how did you get Eff V?

You either combine 2 eff 4 books/ items with eff 4 in an anvil or you get an eff 5 book dealer through villager trading.

TNT in town is not good.
Here, I'll give you a scenario:
1: Player who has use of TNT builds TNT cannon
2: Fires TNT into another offline player's residence, destroying their hard work
3: Player destroys their TNT cannon so nobody knows it was him

+ source of xp
+ a few extra shovels because that's assuming you repair it at one durability
+ roughly 3 anvils

TNT would be specific to a residence so it wouldn't be possible for a player to do that. Probably controlled by flags.

plain, I don't like using my exp.

You're gonna have to if you want to repair..

Trust me, its worth using the exp for.

I repair using other half used shovels... You get a bit more durability that way.

Barely. It is no where near the time and money saved of enchanting and even just getting an unbreaking 3 shovel. I believe that repairing (anvil) with just one enchant is very cheap on the exp.

You'd have to take into account the efficiency of your XP farm. Is it easier to repair E4 shovels 3x as much or repair E4U3 shovels 3x less but for more expense with XP?

But honestly, you're talking about removing over 220,000 blocks.. does it really matter? It's not supposed to be easy anyhow.

And here I am, digging out people's resses with a stone shovel