Are Sims skilling up too quickly?

I didn't want to post this in the bugs thread in case I'm mistaken, but I've noticed recently (like the past month or two, I've not played much so I'm not sure if it happened after any particular patch) that my sims seem to be leveling up really quickly in just about every skill. I thought at first they were skipping levels, but the notification about each level is there so I guess I just miss it. 

In one game a sim got to level 6 painting in just one day. They didn't spend the whole day painting or anything, they interacted with their wife and the welcome wagon, and read a book. They had the creative trait and the natural light lot trait, but even sims without those advantages seem to be zipping up levels.

I tested it with a sim with the traits creative, loves the outdoors and cheerful, and found if they did nothing but paint for six hours they got to level 3 1/2. If they did nothing but practice speech for the same amount of time they got to level 3 charisma. These seem pretty high to me, but it's nothing compared to level 6 in one day - I don't think my other sim could have been painting for 12 hours. 

Is there anywhere that says how quickly Sims should level up? Is this fast or have I just not been paying attention up until now? 😅