one thing I probably didn't mention is we do the program design having already done an in-depth codebase research, with current patterns and architecture surfaced - that actually seeds every step of the flow including even the product part -

but yes if you're working in very small slices then I think it's very feasible to skip program design and just review the code as you go, and resteer live. I do this all the time for tasks that are too big for a oneshot but on the smaller side overall.