Mate, you're overcomplicating this. The real problem isn't the time it takes to diagnose-it's that most SEM "experts" can't translate spend into tangible activation metrics.
I've been on both sides too, and here's the hard truth: if a freelancer can't tell you within the first 30 minutes what your biggest leak is-whether it's wrong targeting, broken ad copy, or a landing page that tanks conversion rate-they're wasting your time. That "it depends" nonsense is a cop-out. Every account has a smoking gun.
You asked about ownership? Fine, that's yours. But the first 30 days should be about one thing: fixing the conversion rate. Not running test campaigns, not "optimising" keywords. I'd benchmark every single campaign against your activation rate-percentage of clicks that actually take the desired action within 72 hours. If that's below 2%, your freelancer is burning budget, not building growth.
The platform race-to-the-bottom pricing is killing accountability. Someone quoted me £300/month to manage a £10k spend account. F*ck that. You get what you pay for.
Stop looking for a guru. Start demanding a clear, metric-driven plan in the first call. If they can't map your spend to a specific activation lift, walk.