The flow I'm using is plan -> technical plan -> execute using TDD.

My level of involvement decreases from step to step. I'm totally in control of the initial plan. I'm giving strong oversight of the technical plan. But by the time it comes to executing, I'm happy to let it completely take over and I'll review either at the end, or break it down into 2 - 4 phases for long plans and I'll review after each phases.

For this final step, which might be 30 minutes, I'll step out and do something else. I want to be sure nothing bad will happen on my machine if I do that, so sandboxing is important.