From Melvor Idle
This page is up to date (v1.0.1).

Template for all the time modifiers for mastery. Splitting off since it's now used for both Mastery and Summoning pages.

These values are sourced from the in-game function getTimePerActionModifierMastery().

Skill Seconds per Action
Firemaking (skill).svg Firemaking 60% of the log's base burn interval
Cooking (skill).svg Cooking 85% of the recipe's base cooking interval
Smithing (skill).svg Smithing 1.7
Fletching (skill).svg Fletching 1.3
Crafting (skill).svg Crafting 1.65
Runecrafting (skill).svg Runecrafting 1.7
Herblore (skill).svg Herblore 1.7
Summoning (skill).svg Summoning 4.85