Anyone here tried something that involves long-term health data tracking?

I recently came across a setup where people are involved in ongoing research that tracks health data over time

it’s not just surveys, more like continuous participation with some structure behind it.

I can see how the data side could be interesting, but i’m not sure what people actually get out of it long term?

Does anyone have experience with something like this and whether it’s actually useful or just sounds good on paper?