I don't think I agree. It really depends on the transaction cost of the thing implemented. If it takes a day to implement something that has a 2x signup rate t

I don't think I agree. It really depends on the transaction cost of the thing implemented. If it takes a day to implement something that has a 2x signup rate that the 20 minute thing, you are clearly making a bad tradeoff. This is engineering. There are no absolutes, just a series of tradeoffs.