I much prefer not having to control other characters PC's if I can at all avoid it. However, I will bot PC's in the following situations.
A)By request
If a player states they will be away for an extended period of time, I will perform actions as per instructions that the player has defined. If no instructions are given, then I will have that character act in such a way to expend as minimal resources as possible, while maintaining actions that they performed earlier(i.e. If the player has activated an effect like Rage or Bardic performance, I will maintain that ability) .
B)By delay
If a player's actions are needed and they haven't posted in the past 24 hours since my last post, then I will bot their actions in the following manner:
If the party is out of combat, and the party is waiting on the PC, then I will make the check based on the PC's sheet, and move to continue the story.
If the party is in combat, then I will delay said PC to the next allied initiative block for the first inactive period. Thereafter, I will treat the PC as if the player has requested the PC to botted, until the player demonstrated that they have returned.
