Intra session recovery in speed training

Hi guys,

I have seen that a good way to base recovery between speed reps is to add 1 minute for every 10 metres.

However, my question is I have noticed that sometimes more recovery is used and how do you judge when you should use more recovery then this general outline (or less?).

Is it more important to use more recovery then this general outline in a competition phase, or are their guidlines to moving away from this formula that any of you have used.

cheers