The way 5e handles checks is garbage because there's no way to invest in an attribute in such a way that you will consistently pass that particular kind of check. It needed to be modified.
lets say you get mid diff check, by shares, how high you can cover it with char build and how much is left to dice?
The RAW:
Typical Difficulty Classes
Task Difficulty DC
Very easy 5
Easy 10
Medium 15
Hard 20
Very hard 25
Nearly impossible 30
To make an ability check, roll a d20 and add the relevant ability modifier.
The ability modifier is your stat plus the proficiency bonus which is modified per level (a flat +2 up to level 5).
Your stats are capped at 15 at the start, so at most you will only be able to get a +4/20% advantage on skill check. You can pass a very easy check with no problem, passing an easy check requires a roll of 6 which is a 75% chance of success (compared to the base 55% chance), passing a medium check requires 11 which is a 50% chance (compared to the 30% chance) so you're going to lose half the time which will feel like all the time, a hard check requires 16, 25% versus 5% (might as well not even bother).
Now with D&D 3.5 you could put 4, even 5 points for certain races into an attribute and put four points into the skill itself at level one for a +8/9 40%/45% bonus which is far greater and likely to result in consistent success (and there are feats and such that you could let you have even more of a bonus but that's overkill for the available 3/3.5 crpgs ime).
And as noted by that proficiency chart, you can't just gain a level to get an advantage in 5e. You have to gain 4 to gain a measly +1.