Instead of waiting for them to walk all the way across the universe when they're doing their building, if you interrupt them part-way & cause them to drop what they had (assuming they're removing & not building) does it still work?

I haven't tried it yet, yaelle, but I don't think so.

Nope. You get the points when the goods are delivered and put into place. You can only interrupt breeding couples, healers, and sometimes researchers.

what you can do is hurry them a bit.. when clearing the beach after they drop the wood you can pick them up and drop them back...same with clearing the blockage

It doesn't work in terms of building getting done, but it does work in terms of skill points getting earned. Eg, when they're clearing the beach, as soon as they pick up the plank and start walking away, they've got their skill point boost. If you're just interesting in training up their skills, you can pick them up and redrop them at that point. I do this with the berry bush when training new farmers. The point at which a berry dish appears in their hands is when they've learnt more skill. No need to wait for them to carry those berries all the way to the foodpile and back, if you don't actually need the food.

I think it works one-way. You have to let them carry the goods away, but you can airlift them back to the job site.

Same with farmers, IIRC.

You see the skill up message picking up a rock at the blockage but if building a hut it's when they hammer it in place. I haven't checked the beach yet. But to be honest I don't really trust the messages so much anymore. You get a whole lot of bogus heal ones. I tried to boost an adept to master on the blockage by picking them up after seeing the skill up but it never looked like it moved. Now true it takes alot to go to master but after 30 tries, with messages, and no movement at all I just don't trust them anymore.