I have designed and implemented over 50 different applications in my 20 years of writing software. Most of us that have been doing this since the '80s have.

Few apps are ever rip roaring successes, most of mine were either prototypes or software for the use of small work groups. The basic process of designing and implementing is the same, refinement is usually more of a budgetary and market size issue.

My approach to application design tends to be more customer centric an iterative than anything else. Experience has shown that few people can ever hit better than 10% or 20% on anticipating requirements, so rather than expecting customers to do something that seems unlikely, I attempt to be flexible and move quickly through many iterations.

This is also another huge advantage for an approach using code generation. By doing as much of the database table IO through code generation as I can, this frees up 80% of the time to do the changes that keep a customer on target.