Honestly, as long as the collision lets you walk over it smoothly without getting caught in the gap between the terrain and the object, I think this is fine. Having it flush or overlapping would probably lead to z-fighting or other weird collision bugs.
Having done it for a living for a few months, you cannot possibly imagine how bad it gets.
No, seriously. I already had very little faith in humanity going in, and thought I’d seen the worst the internet had to offer. Scraping the actual bottom of the barrel is difficult to even describe. I had to force a stunned sense of humor about it to detach myself a bit as a coping mechanism.