You don't mention if you're running command, conventional, LC, LC+. You didn't give an overall size...3x9 loop, or 20x40 sprawling carpet monster.
If you run lit passenger cars with blocks you have to be concerned with thier wiring. (never leave a set of rollers bridging two blocks for long; phased or not.)
For command, LC, LC+ etc. you need constant power, so you put pins in the center rails to create 2 "blocks". Then each transformer feeds one block. Turn them on, make sure you dont excede their max voltage. Run the train via the systems remote.
However, try the drops is first. Use 12g to 14gauge set of wires feeding the track at various points; drops. Some folk do only a few, some folk do one nearly every other track section.
The short of it is copper wire provides a better electrical path than track does.
For small conventional, one transformer per loop is what you want. If you have a ton of track two might be easier to handle, but the extra throttle isnti a help really. . If you run a grade, it might be handy to have two. One on high to climb, on on low to come down.
I'd think about two loops and two engines if conventional running is what you do. That or a siding that uses its own power.
If you connect the loops, then you'd set up blocks between the turnouts. You want turnouts to remain powered by the main track they support. Which loop powers the rails between two loop is a choice (with trick options if fancy=fun)
