In response to a discussion I had with Shephard about reclaiming during patrol here:
https://www.youtube.com/watch?v=A2w0n4YVJng
Some testing, see attached replay (click player name to see the income, and speed up the replay).
I'd say that a patrolling engineer reclaims until roughly [mass is 100% and energy 75%] or [mass 75% and energy 100%] and then moves on. And if mass reaches 80% and energy is low, then the engy will go look for trees in stead of filling up mass to 100% with wrecks.
So if for example you have a ship graveyard in front of your base, that you want to reclaim quickly, overflowing mass to your mates (assuming that energy storage is full), then I'd say that patrol would not work, you'd have to set out specific reclaim orders.
(I am myself of course too often forgetting to reclaim wrecks, I'm just trying to figure out how things work.)