There should be a ! over the rest icon when there is an event, similar to when a companion wants to talk to you.
The game should not tell the players how often they should rest.
The game should also tell you that resting will fail some quests while it is needed to advance others.
It does not help that the game is usually timeless and the timer only starts when you reach a certain location or reach a certain point of a quest.
Currently it is absolutely not clear when exactly a timer starts.
So far I did not fail a quest because of resting. It seems clear that you should not rest while you are in a burning building or you try to save a child from monsters.
But there was one point where I was running all over the map to find out how to continue a quest and then it turns out that I had to rest so that some NPC move from one place to another.
BTW, there is a reason to rest often even when you are not exhausted after a battle: Merchants have limited gold to buy all the stuff you find.
The fact that they also restock rations makes food a non issue, in the unlikely case you do not find enough food on your own.
Prof. Dr. Dr. Mad S. Tist
World leading expert of artificial stupidity.
Because there are too many people who work on artificial intelligence already
