House Rules

• Your character can learn new proficiencies over time, if they persist at working at the task.  The longer they spend working at it, the more likely they are to succeed.
• Each long rest that your character is willing and able to practice the skill, you can roll to see if they succeed.  The first long rest, you roll eleven d20s, and they must all pass the DC for your character to succeed.  This is exceedingly unlikely.  But the second long rest, you only need to roll ten — persistent practice has made it a little easier for your character to really understand their goal.
• Each long rest, you reduce the number of d20s by one.  After ten long rests, you’re only rolling a single d20 each time.  Thus, your chance of gaining proficiency in a new skill starts at a tiny 0.0000000000005%, but eventually increases to 5% each long rest.

When a party encounters a monster, players often want to know what their character knows about the monster. This resolves with an Intelligence check, adding a skill modifier such as Arcana, History, Nature, or Religion. 

Using different skills for different monsters also means that some of the lesser-used skills will come in handy. It might make sense for a character to have some knowledge of history, but in the regular game, that doesn’t come up very often when compared to something like Stealth.