You should pay 10k to 15k or less for the service.  10% on a million dollar build is beyond silliness to me.For 100k to 120k in design fees, I'd want the Property Brothers themselves to come down and design the thing. :-)

I've learned that the unexpected always happens, whether it's delays or unforeseen expenses, so having a system in place to monitor finances regularly helps make adjustments before they become bigger issues.

Meanwhile, your expenses, like debt service, taxes, insurance, and maintenance, continue.

. - Products & Services enable us to track each 'phase' of the rehab. - Projects give us visibility on my projects- My CPA can easily access the reports for tax preparation.

Neither outcome is good for you.I give some approximations of each expense category in The Hands-Off Investor, but the best way to nail down operating costs is to look at the property's historical performance.For example, Contract Services and Utilities. 

However I have great units and we provide excellent customer service so I generally have little turnover.

Small investors just can't go there today and be compliant or economical so get a servicer.

Evaluate and execute flips using software, monitor rehab, and plan exit strategies.

I asked about Zelle, it is only a service for US Banks, not internationally.     

I have a duplex that I originally intended to have serviced by individual heatings systems, but ended up installing a single system that's large enough to heat the whole building.