One thing I’ve noticed is that effort may be saved but not as much time. The agent can certainly type faster than me but I have to sit there and watch it work and then check its work when done. There’s certainly some time savings but not what you think.
Another thing I've noticed is that using AI, I'm less likely to give existing code another look to see if there's already something in it that does what I need. It's so simple to get the AI to spin up a new class / method that gets close to what I want, so sometimes I end up "giving orders first, asking questions later" and only later realizing that I've duplicated functionality.
Always have another agent around that is just reviewing code. "Look for duplicate code, code smells, bad architecture, future scalability problems..."
I usually keep one agent/prompt/context ripping through new features and another 1-3 agents/prompts/contexts reviewing, testing, planning.