That cut of the rent ends up being around all of the cash flow for a newly bought property, and in many markets ends up being more than the initial cash flow. It’s a second job with irregular on-call.

Well, then you've leveraged too highly. Estate agents here take a fairly small percentage of the rent to manage all of this, so it takes a fairly small deposit before your rental income less management fees can't cover the remaining mortgage.

Property management companies in the US take somewhere in the 8-12% range. Is it dramatically lower wherever you are?

Towards the low end of that, but even at 12% it just means you can afford lower leverage.