Currently the hearth magic contemplation is it halves the current remaining time of a curio, which means its most optimal to use immediately after you put in your study window.
The issue with is I would need to set real life alarms to log in my character when my curio finishes to get the most out of this, im not surprised if somewhere in this community there is a bot for this.
But its quite easily addressed without changing the actual balance by reducing the remaining study time by 50% of the original total. as-long as its impossible to use twice on the same curio.