Duncan,
I thing the 18" is a fine idea. While some may prefer longer, the 18" will satisfy all needs as fer as a usable variety pack. I am sure the intent is not for folks to buy the variety pack as a staple, rather just a starter kit.
I see it being useful for multiple reasons, both to provide a variety pack, but also it will enable testing of all of the features of the welder upon receipt, on multiple materials, to ensure it is functioning properly.
Everlast 200DX
Everlast PT185
Shoptask 3-in-1 (not currently in my garage, but I own it...)
Any day on a motorcycle like this that ends just needing parts and labor is a good day.
4.82, 158.67mph 1/8th mile 7.350, 200.35mph 1/4 mile