2x portage except when safety is concern. The infamous staircase portage into Russel comes into mind. 3x to top then 2x to Russell.

I don't think there is anyone "best" way,  but there are a few really bad ones.

Blocking the portage on either end is a big no-no.
Whatever style suits you, make it a routine and stick with it. People who just grab whatever is close each time, end up losing things sooner of later or have to repeat a trip because they forgot something or assumed someone else got it. :-?

If your a "roadrunner" and really traveling fast and light ( nothing the matter with that), that's one thing, but loading your self down to the point of exhaustion/ safety issue, because your trying to 1x/2x, because you think your saving time is misguided.
Better to make efficient non-stop( if possible) and quick returns ( picture time) than stop for frequent breaks because your exhausted or worse you take a tumble and injure yourself.
I bet if you timed yourself/others trying to carry to much versus quick and smart, you'd see the time savings is very minimal if at all.

I've seem more than a few paddlers bust butt to avoid an extra trip across and end up taking a break at put-in because they were wiped out from the effort. ;)