You know, for an entire 2 year 5E campaign, I made the following rule changes:
- Everyone, including all npcs and monsters, got proficiency in all saves (so scaling remains smooth and someone's weak save doesn't become weaker and weaker).
- Passive Perception gets rolled into Wisdom saves/defenses.
- The Investigate skill takes Perception's active actions (like searching for someone or an active perception check).
- If an ability gives you Perception proficiency, it's Investigate proficiency instead.
Perception is just too much of a must have skill. It should be harder to sneak up on a high level person than a low level person, but plenty of classes don't get perception proficiency. I wanted all skills to be things you actively do, not passive things.