I've run into this in a side project I'm working on, where my indecision over which ownership models are actually workable in the API to satisfy the needs I have means almost all of the coding is spent just proving I can get an ownership model working over having a skeleton code that can do something. And still, even as lacking as functionality as this codebase is, swapping to a new ownership model takes several minutes of coding. Trying to do this kind of exploration on a codebase that has real functionality would mean spending hours of change just to move some property from here to there.