Rand said he had the original/prototype of a paralis net, which even third Age channellers right away identified as a wartime device. It seems terribly obvious they were designed during the War of Shadow, and the first prototype went to the Light's leader... There are a few clues they may have been a late war invention - that would explain their relative rarity.

It's possible wells allow someone who's shielded to channel nonetheless, and thus to help break your shield, or to create an emergency gateway, or a weapon to kill their opponent by surprise when shielded might be their true purpose, at least when they're included in a paralis net.

I'm not quite sure wells can be used in a stedding at all. Stedding negate the One Power in some way. You cannot channel into it from the outside, RJ confirmed that. That's very different from Far Madding, where the Guardian strictly negate access to the True Source, but does not affect weaves. With a powerful san'angreal, you could level Far Madding to the ground with the Power. This wouldn't work on a stedding...

A more likely peace time use for wells would be as an emergency power source, in case a device for any reason didn't have access to the Standing Flows. Ie: a battery for ter'angreal.

The theory being blocking out the source etc. may well have existed in the AOL. It's just terribly hard to see why would such devices be built by the Aes Sedai.

It's not impossible something like dreamspikes also existed. They would have been useful for emergencies, fir eg: if there's a crisis of some kind at a designated travelling area and the authority nedeed to stop the opening of accidental gateways while it's being dealt with. There would be no real reason for these devices to be widespread, or of easy access to "civilians" (a bit like Binders and such).

The war would have sparked the AS to look at a lot of objects of great or extremely limited use before in the light of their new military potential, and at the same way at OP theory that had no obvious or great application in peace time but could be very useful in war. Shielding other channellers for instance was probably of no great use in the AOL.