It's me again............sorry !!! 
When a recipe stipulates to stretch and fold very rarely does it tell you how many times to do it, or how to do it.
In my short experience of sourdough baking I have just been doing the stretch and fold once each side when the S & F is required 
confused I'm not surprised let me explain if I can.
I hold the dough up from the bowl by the top of the dough, I shake it gently till it drops into a long thin length, I then fold the top half into the middle, then I fold the bottom half up also into the middle to meet the top half. I then turn the dough 90 degrees clockwise ( i am now holding the side of the dough) and do the same thing again.................hence S & F both sides I repeat that at the intervals required as explained in the recipe.
So back to my question should I stretch and fold at each interval more than I do already ? and if I should is there a technique for knowing how many you should do and when is enough.
I realise that S & F helps to build the dough strength but should it be Hercules strong or just Mighty Mouse strength 
Thanks in advance of an answer
regards
Linda 
Replies
You understanding of a stretch and fold is correct. It helps with gluten development. It also ensures even temperature of the dough. There are several different ways to build gluten. One is by a traditional knead. The other, which is a lot easier, is to use folds. Unfortunately, ease comes with a huge investment of time. For example, when I make a french baguette, I will fold the dought two times over a 2.5 hour rise. I remember the first time I used this method. I was confident that it would not work. I was convinced that the only way to build up gluten was to work up a sweat by kneading. When you do the first fold, the dough is extremely extensible because there is little in the way of gluten development. However, as you move into the subsequent folds, you start to feel the difference in the dough. The gluten develops quickly. As to whether you want the dough to have Hecules or Mighty Mouse strength, it all depends on the bread recipe. Hope this helps some!
Hello Linda,
I think of it a envelop folds. Your stretch the dough into roughly a rectangular shape and fold the top long edge two thirds of the way to the bottom edge. You now have a narrower strip with half double thickness and half single thickness. You then take the single thickness edge and fold it up and over so that you have a triple thickness one third of the original width. You then repeat that fold right and left so that you end up with a 'pile' of nine original thicknesses.
You then leave it for your hour or whatever time and repeat the process.
By the third S&F you should be getting close to the 'window' stage of dough development and by the fourth you will possibly have to hold the dough in place to get the stretch done as the gluten will be so strong. In the early stages the friction between the dough and the bench will be sufficient to allow the stretch to occur.
Once you have experienced it, you will be amazed at the change in the properties of the dough.
Good luck with your projects.
Farinam