As others have mentioned, many game systems lack incremental progress.
RuneQuest had percentile skills, each time you used one you gave it a tick, and after the adventure you had to roll above your current skill level to be able to add a few points to it - and those points were random. Thus, progress from 20% to 30% tended to be rapid, and progress from 80% to 90% much slower. This well-reflects the real world diminishing returns of efforts in any skill area - your first 100 hours learning a language or driving teach you a lot more than does your 10th 100 hours.
Classic Traveller has as a default no skill advancement at all. However, you can choose to try to improve something. Once you start lessons you get a temporary boost, then after some years you make a dedication throw (8+ on 2d6, ie 15/36 or 42% chance of success) to see if it sticks. That's like the people who come to my gym for a while and then leave - after 3-6 months they know what to do, but do they actually do it on their own?
In reality, there are only four meaningful skill levels: shit, suck, good, great. To be not shit doesn't take much time or effort. Being good takes a lot of time and effort, and great takes dedicating your life to that thing. People do have natural talent levels, but rarer than talent is people willing to make the effort to be something other than just not shit. Most people are shit at almost everything, and not shit - suck - at a few things. Most people aren't good at anything, let alone great.
That's reality. Whether you care about reality in a game with orcs and elves and fireballs and wands of resurrection or warp drives and phasers and unobtanium is another matter.