jgsugden
Legend
We're not talking 'balance' here. We're talking 'power'. That is what the OP requested we address. I answered about how powerful it can be. I agree that extremes can be misleading when considering how effective an ability can be for most PCs - but here we're addressing how powerful smite can be.I said in the shield discussion...extreme CharOp builds aren't a good way of determining balance in the system.
Not me - I was the DM.I'm surprised you had enough spell slots to power all 8 strikes!
However, you get 2 spells as a '1st level' caster, 3 at 2nd, 6 at 3rd, 7 at 4th and 9 at 5th (which is a 9th level paladin). In an alpha strike build, where you want to drop as much damage as you can in round one to try to prevent the target from ever going, paladins have no trouble having enough slots. So, even if you hit with all of those attacks and used one slot to cast haste - you're covered.
In my experience, these types of paladin builds burn spell slots fast, but often have a slot or two left over - which makes them feel a lot more like a warlock than other spellcasters. They use a wee tad of magic and then just deal a lot of damage.