I think at least in the construction branch, the skillpoints rewarded should be based on the weight which got used in building. Also finishing a building should get a bonus as well, to counter waste of materials for fast leveling.
Cooking might get more skillpoints depending on what is being cooked. (More ingredients? More points.)
Herbalist might be granted a bonus if a previously unknown effect has been found.
Smithing/Armorsmith might get skillpoints depending on how many ores the used materials have been worth.
Digging and Mining might get their skillpoints depending on what material is being gathered?
Something like that?