You want to build your pack according to how much current your battery pack can make. At least, that’s how I build mine. You want a 12s5p Molicel p42a, so you’re looking at 20 to 30 amps per series connection. I’m not so fond of doubling nickel strip. Nickel to nickel welds are about half as strong as nickel to steel welds. However, I see nothing wrong with doubling your p groups, but I think series connections should be nickel to steel, so, never doubled. There’s a few tricks to get more current out of nickel striping.
You can double the tabs as seen here. This doubles the amount of current you can get, but then you have to collect the current from both sides of your p-groups with something like braided copper, and only after insulating the living daylights out of them.
That’s how I built this pack: 🖼 Pictures and Nothing Else! - #1277 by leadBreather
But honestly, you’re probably better off going with custom tabs cut down from that 30 or 50mm striping. It’s much easier, as you only have to collect current from one side of the battery.