I never turn it off on board. The "cookie trail" as we call it, paints constantly on the little screen. I watch our swing increase as the tide falls, tighten up on the flow. I watch wind shifts paint the new slot we're pushed into, it's constant movement. I use it to measure(estimates, but surprising accuracy) back to where we dropped anchor heading into the wind earlier.

It instantly alerts me to changes in our position in the middle of the night if I get up to check on things. There's nothing like seeing that dark half moon on the little screen in a blow at 3 am, that shows our anchor is very well set(yes I can still take a bearing ).

And yes, the trail is a big part of navigating out in the dark or if we have to move in the middle of the night.