Unbelievable!
Peacy, braking and turning at the same time are a recipe for disaster for all but the very talented (ie, me) on road or track. Do your braking in a straight line, and you'll be more than fast enough around the supermarket car park.
The point of heel and toe is to get to the correct gear with the minimum of disturbance to the car's stability while braking
before a corner. There's a degree of 'snatch' as the engine speed matches the road speed in a new, lower gear, and blipping the throttle with your 'heel' (my little toe) with the clutch engaged - while braking all the time removes this.
Useful in every day driving for the abovementioned reason, and also for reducing transmission wear considerably; not to mention impressing whole bus queues
