For me, LSD is a much more potent substance in terms of overall effects (and the result of them) than say, shrooms. Therefore, dosing LSD weekly would not be something I'm interested in.

However, I've spent a reasonable time frame where I was tripping shrooms just about every weekend, and the effects are pretty benign overall. Ditto with DMT, except even more often. That being said, I did notice some weirdness. Describing this will be hard...it's as if when I can't fully make out what something is, my mind gets -much- more creative with what it thinks it sees, causing me temporarily to think I see things that I don't.

I mostly notice this when I'm driving at night. I'll think I see something cross my path, like a cat, but nothing was there. Or if I'm looking at a dark scene, my brain has trouble deciphering what exactly I'm looking at, and comes up with some really trippy off the wall explanation until I finally get a grip on what the actual surroundings are. I hope this makes sense.

Perhaps that could be considered a mild form of HPPD, but I don't know. It seems more like a re-wiring of my brain to search deeper for explanations of things. (Maybe that's synonymous?)

In any case, this effect lessens considerably over time after not being exposed to psychedelics.