Normalization in progress makes it more like the left. Example of working out and hitting a new plateau or fitness level, which is now your baseline and you fluctuate and start all over (You are still progressing). This is why you note progress with values and not feelings (Of course this doesnt work well with certain areas that are inherently subjective).

Or on a long time scale it would be logarithmic, relative to certain factors, and you have an absolute limit.