Power to loops

Here's where incorrect terminology used by Lionel gets sketchy and people get lost. By "controlled by switches" to you mean toggle switches, or a turnout (proper)

But no. Each isolated section track does not need it's own transformer, but you could do it that was if you wanted. It's always suggested to jump power over turnouts rather than draw thru them. A section to be controlled by a toggle/etc needs power isolation by pins.

You should however check the phaseing on two or more transformers used together. Look up Phasing Lionel Transformers on YouTube for a good video that Lionel published there. Some bricks accidently came from Lionel in reversed phase. Only relavent if used with multiple transformer setups.(watch video)

Not toggles but rail track turn outs to a different track. I hope I am clear. With 3 track lines is one ZW enough or should I have more power blocks

Larry Lloyd posted:

fasttrack 3 loops 72 60 48. Should I have a separate power supply to each they are connected by switches  should they be electrically isolated. Running legacy

NO. That's the beauty of running command.

Run a bus down the center of the layout to provide power and common. Connect the track feeds to those two wires. 12, 3, 6 & 9 o'clock on all loops.

Why?

If you find that you are running out of power or taxing one transformer, it's easy to run a second bus (one hot wire) and isolate the loops and move the track feeds for a loop.

Common (black, neutral) should be all connected and transformers phased, so only additional Hot needed.

Permanent or somewhat permanent layout?

Plan ahead when building and pull the wire on the 1 3/8" piece between the adjoining turn-outs when assembling the track, but still use one transformer and one bus to distribute power.