I mostly agree, although it's worth noting that there are probably some fixed overheads of being employed that eat up some of the otherwise expected benefits. Let's consider a scenario where there are 4h average fixed overhead for working at a company. Now let's run the 0.6 time vs. 1.0 time scenarios.
1.0 time. 40h - 4h overhead = 36h. Pay = 1. Work-to-pay ratio is 36h:1p.
0.6 time. 24h - 4h overhead = 20h. Pay = 0.6. Work to pay ratio is 33h:1p. You'd have to suppose that the 0.6 time worker is at least 1.1x as productive per hour just to break even. If you provide benefits that don't scale with fractional work you need even more of a productivity edge to justify it.
The corollary of this is that you'd really better make sure you have little fixed overhead time for your workers if they are working fractional time.
1.0 time. 40h - 4h overhead = 36h. Pay = 1. Work-to-pay ratio is 36h:1p.
0.6 time. 24h - 4h overhead = 20h. Pay = 0.6. Work to pay ratio is 33h:1p. You'd have to suppose that the 0.6 time worker is at least 1.1x as productive per hour just to break even. If you provide benefits that don't scale with fractional work you need even more of a productivity edge to justify it.
The corollary of this is that you'd really better make sure you have little fixed overhead time for your workers if they are working fractional time.