The theory of using ollas is sound, so you may just need to decide if it is worth it for you.

I saw a similar alternative with gallon jugs of milk or water (poke holes in the jug near bottom and situate it near a plant or buried up to the neck like ollas). Leave the lid on so the built-up pressure will let the water out slowly. You could try the milk jug option for a few plants to see if you see some differences in growth. Keep a few plants without the jug so you can make a comparison, though for trees, it might take a while to see some growth differences.

If you then like it, then I can see how a 5 gallon bucket or larger tub with a pvc pipe sticking out, can be utilized in a similar fashion in case you want a larger reservoir. Even cat litter buckets, if you know anyone with cats.

For a few plants are OK, but when you have a long bed you'll want a more spaced system. I design what I call my PipeOlla. A 4" PVC pipe with a Horizontal Float valve in one end and Fiber Wicks at set intervals reaching out up to 24" long.

Once its installed, just turn on a water hose, 1/2 to a full turn and get 24/7 watering.

It seems to me that they could be amazing slug breeding grounds.