If there’s already a mechanic for it, don’t add a new one.
One of the things that 5th edition does a lot better than 3.5 is level scaling of skills and class features. Rather than having a separate table for each class’ saving throws, base attack bonuses, skills and skill points, there is just one number: proficiency. It streamlines the gameplay immensely, and actually makes sense to players. Not to mention it lets the DM make level-appropriate rolls on the fly for things which are not covered by the base skills. Doing something your character should be good at? Roll with proficiency!
So if you’re brewing up a new feature, then make use of structures that already exist. Don’t add in new numerical tables to count something if you can piggyback on one that’s already there. If you want your feature to scale with level, you better make sure you either just use the character levels or their proficiency!