This is a fair point. Character advancement in CoC before 7e was very slow.
My home rules include
1. grouping up most skills into categories such that once any skill passes 50 and again at 90 then each linked skill with at least 5% gets a +5% bonus; (ie climb, jump, ride &swim is one category and charm, fast talk, persuade & psychology is another etc)
2. having between adventure scenes where players desc what their character is doing and thus gets a roll to improve something (like Delta Green Home scenes); and
3. If we play multiple sessions between experience rolls allowing people to get more than one check to have a chance to improve a skill (still only 1d10 improvement per adventure)
This and the 1d10 improvement (vs the old 1d6) has made a big change to character advancement.
