How many specific abilities should each trait grant?

Definitions:

• Trait: a single, atomic thing you can take during build or levelup (3e examples: feat, wizard spell; S7 examples: a "skill", power skill, or power source)
• Abilities: buttons you can press in-game

Some examples:

• In 3e, a wizard can choose 2 spells per level. Each is 1 trait, granting 1 abilities.
• In some versions of S7, you choose a single power skill (or rank), instantly gaining multiple abilities.
• In other versions, you choose a skill as a trait, then spend some other currency to gain abilities.
• On yet other versions, you only gain powers 1-for-1.

Observations:

• Feats
  • In the various systems where feats/maneuvers/exploits exist in some form, they either come as 1-trait-N-abilities or 1-trait-1-ability
    • In 1:N, the complaint is that there are too many abilities on the sheet to keep track of
    • In 1:1, the complaint is that you don't know what abilities you have, and are forced to look them up
• Spells/Powers
  • In 1:N systems, the complaint is that you don't know what abilities you have, and are forced to look them up
  • In 1:1 systems, the complaint is that there are too many abilities on the sheet to keep track of

There's no obvious winner here. But consider the 5e Advanced character sheets such as </5e Advanced/characters/Phobos.md>. The idea of an all-in-one sheet seems appealing, especially in a more pleasing UI than an Excel sheet. Links to wikis etc are fine, but an atomic, unchanging sheet with no dependencies seems like a good thing.

Of course, that doesn't imply anything about the process of choosing abilities.