hey guys

when does it become necessary to use a powerbox system?

and also what are the main reasons to use one?

mainly to be able to use 2 or more servos on one channel?

how about amp drainage via receiver to servos if one uses HV servos?

120CC plus airframes then maybe.

Most computer radios these days will do multi servos on one channel and HV servos without a Powerbox

Not sure about a power box. But a smart fly will act as a power filter. In other words it will clean up and regulate the voltage. Allows 5V to the receiver and up to 6.5V to the servos. It's a batt share. Servo match. And optic kill.
I run one on my 100CC Edge and another on my 170CC Sukhoi

ok sounds like powerboxes are more about being fancy these days then

There's applications where they are either needed or will make life a lot easier but you're getting into big and complicated stuff before you reach that point.