Repeaters go where the power and purpose is and often there is not a lot of flexibility on that. Child devices should go where they best monitor the condition they were allocated for. A strong Zigbee network should really allow you to do that without overthinking it.
I think there are just a number of poor zigbee repeating devices out there. I got into this:
I added 6 Sonoff S31 and sold off 2 x Samsung Smart Plugs to pay for them:
Zigbee network went down the toilet in terms of reliability. Bought and XBee to figure it out.
Conluded the Sonoff S31's were crap.
Sold all of my S31's and bought 2 Sylvania smart plugs and 4 mini USB repeaters.
