You might want to be a bit fancier with inclusion/exclusion of the area or even volume involved if there's a potentially concave zone where you don't want them 'walking straight between the points of a crescent Moon' for any reason. You can probably define the whole non-FB side of the pool as a WebBurrow (to coin a name), include the Loom they collect to in it as well and I also suggest you add the bedrooms/dining/drinking areas of your choice as well (if you don't want to aggressively work them until they can't stand it any more) unless you already have NeedsBurrow(s) set up and you can just give them 'membership' of both/all when you juggle them into the job (without losing track of who-is-in-what after several improperly implemented job-swaps). You don't need to be 'spot perfect', though.

If you bear this in mind, I think you can probably keep them wandering too far from the 'safe' collection mass and thus not into areas you don't want them to (and are webbed, which might even be the dangerous aspect, such as you describe).

It can be highly discontinuous (e.g., I presume from your read idea, at webs-to-be-collected tiles and the collecting workshop only) but it doesn't stop transit via whatever terrain might be pathed through on the way to the web, web to workshop, workshop back to web and (if ever Needs require) food/drink sources from whereverthehelltheyarewhentheyUrgentlyNeed. Burrows define where a member of that burrow can pick up a job(-end-point, ?either end?), unless something has changed that I haven't noticed.

Dwarf fortress burrow res