Age Categories in 5.5e

So, 5e and 5.5e doesn't have Age Categories. I'm on the record as enjoying aging effects, but admittedly, it does get a bit fiddly, doesn't it. Figuring out what age category an elf is as compared to a human of the same age, or whatever? Fiddly.

The Modifiers

I do rather like 3.5e's numbers:

• At middle age, a character gains -1 to Str, Dex, and Con; +1 to Int, Wis, and Cha
• At old age, a character gains an additional -2 to Str, Dex, and Con; +1 to Int, Wis, and Cha
• At venerable age, a character gains an additional -3 to Str, Dex, and Con; +1 to Int, Wis, and Cha

So being Middle-Aged is strictly a sidegrade; Old is a downgrade (with a silver lining); Venerable is an even worse downgrade (with a silver lining). Extreme min/maxers might choose to be Old or Venerable; Middle Age is an eminently reasonable choice for a moderate min/maxer.

What Age Category Am I?

We can probably mostly basically just use 3.5e's numbers for what age category a character of a given species is is at any given age.

(I believe 5.x canon is that elves age like humans until adulthood, and then just stay there; the relevant 3.5e charts indicate that they used to definitively hit Adulthood at 110 years; we could split the difference and let them Young Adult at a more human-like age)

Aging Effects

I used to use specific year amounts for aging magic and effects, but I'm leaning towards, instead: you don't advance specific year numbers; if you fail a save, you straight-up advance an age category; elves just have advantage on the save.

Maybe mix it up with a touch of what 3.5e used to have you do for Negative Levels: at the end of the day, make a save vs it becoming permanent. ...no, I low-key hate that, because I hated that about NLs in 3.5e.

Ooooh, here's an idea: You know how if you have 6 levels of Exhaustion, you just straight-up die? What if, instead of death, if you have 6 levels of Exhaustion (perhaps: "and at least one of them is from a magical or supernatural effect"), you straight-up advance an age category? Or maybe you go unconscious at Exhaustion 6 either way, and if you fail a save you also advance an age category?