As far as adages go, that's wholly incomplete, and generally mitigable with good product planning. Either way, if it's taking just as long to write the generic

As far as adages go, that's wholly incomplete, and generally mitigable with good product planning. Either way, if it's taking just as long to write the generic CRUD of your application as it took to write the application itself, either your application is quite trivial, or you're doing something very wrong. In practice, for most people, the "last 5%" doesn't get added in until after deployment, if at all. Regardless, if you're proving a market, and the highest priority is in determining whether or not there's money to be made on a product at all, the 95% guy is an ace in the hole. The GP even admits that yes, the 100% guys are better, but they are indeed far rarer to come across, and usually involves other trade-offs.