When I built my original garden railway nearly 20 years ago now, cash was short, so I separated out control into three layers. The top two layers were housed in a home made portable box, that lived in the garage and was lifted out to run the railway and plugged into a 25 way computer plug / socket that lived in a waterproof box screwed to a paving slab and sealed with silicon. A long lead connected the box to a socket in the house for mains power - not ideal.
- The top layer was a Aristo Train Engineer that provided wireless track power control, run from a Gaugemaster power supply.
- The second layer controlled the (I think I had three) points via a mimic panel and run from a Scalextrix 12v power supply driving LGB point motors.
- The third layer was entirely "ground based" and is relevant to your question. On my railway, one rail was common and the other was selectively isolated by LGB yellow insulated fishplates, where isolation was needed to hold locomotives. EPL switches were wired to the mainline sections and power was switched, on or off enabling locomotives to be held in loops or sidings.
This worked reliably (usually with a pre-season solder fest, using a 100w soldering iron, of dry or failed joints) until the last sections were removed this year, mainly to reduce the amount of maintenance because the "Triang Hornby" style self isolating points are no longer needed following an upgrade to DCC a couple of years ago.
I hope this helps a bit
Tony D