Hi John,
I used to ridge my Potatoes but I now use a different system.
If you use close spacing more tubers are pushed towards the surface, become exposed to sunlight and are then inedible. Therefore you need to earth up.
A common spacing quoted for early potatoes is 30cm each way and around 4″ deep.
I have found that if I space them at 18″ and plant 6″ deep I don’t get any tubers appearing above ground thus avoiding the need to earth up.
Harvests are not appreciably different but at 18″ you get more larger tubers.
Earthing up might still be necessary if you live in a very windy location to help support the plants during growth, as you would with Cabbages for example.
As for the digging this is unavoidable with this crop. Not only do you have to dig but you also need to be thorough about it in order not to leave any tubers which will grow again next season in what might then be your Carrot bed!
If your using a 4 year rotation your only going to dig a particular area once every 4 years.
Don.