Few Cloudy - I maintain that this IS about track miles/speed control, NOT holding fuel. There is at least one other active thread on R&N where that matter is discussed at length.
Most pilots plan holding fuel according to experience. (I think the rec. from the CAA was 20 min BTW). I personally need to look at the amount of fuel with which I will LEAVE the holding pattern to start my approach. An EAT will give you this. I then 'estimate' how much I will burn after that. Obviously if the latter burn is significantly higher it will eat into my alternate fuel and could put a comfortable diversion option into the 'anxious' box, unless I know about it and build it in to my reserves calculations.
So, if we can reduce the approach fuel, we can increase the available hold fuel, regardless of whether I have 10/20 or 30 mins extra. Indeed I could hold for an hour or two and still run short on an unexpected extended 'draggy' approach.