Wholegrain flour in my country

You can soak as much or as little of the flour as you wish, Ilse.  I'd probably choose to soak all of it but that's just my preference.  I'm not sure that I could produce tangible evidence that it is better than soaking just half the flour.  The one thing to remember with the flours that you are using is that a portion of the bran is small enough to pass through whatever sieve you may have used to separate the larger pieces of bran from the flour.  That residual, fine-grained bran in the unsoaked half of the flour will obviously not be as hydrated as the same bran in the soaked half of the flour.

The type and degree of kneading that you choose should be aligned with the characteristics of the bread that you want to produce.  Are you working with a high-hydration, hearth-style loaf in which you want an open crumb with large, irregular bubbles?  In that case, hand kneading may not even be practical, depending on how wet the dough is.  If so, stretch and folds will work very nicely to produce the desired outcome.  Or, are you working with a sandwich-style bread, typically baked in a pan?  If so, you want a finely-textured, smooth crumb characterized by very small bubbles of uniform size.  In that case, extensive kneading of 10-20 minutes would be appropriate with no stretch and folds required.  Those are sort of the outer extremes, with lots of room in between for using various kneading techniques and timing.

Shh!  Don't let the rest of the Loafers know, but I rarely ever check for windowpane in my doughs.  Most of the time I bake breads with fairly high wholegrain content and I don't necessarily want something that is worked enough to allow a windowpane to form.  Even if I did, it would be very hard to do with all those bran bits disrupting the gluten mesh.  Let's just keep this our little secret.  Mum's the word!

Paul

I wasn't aware that you had something like that to contend with. 

You may want to think of "better" in the context of "Does it look/taste/behave the way that I want?"  If the stretch and fold technique produces a loaf that meets your needs, then you are already in a good place.  If you want something a bit different than you are presently achieving, then some tweaking in process might be appropriate.  If you use the Search tool here (it's that little white box at the upper right-hand corner of the page) and look for French fold or slap and fold or Bertinet, you will find some videos that show a technique that produces a well-kneaded dough with very little effort.  How that motion will feel to your shoulder, I can't say.  It does produce a smoother, more uniform crumb than simple stretch and folds.  And it is much quicker than the traditional push-turn-fold method of kneading on the countertop.  That's just one option.

If you were to using "kneading technique" (minus the quotation marks) as your search term, you will also find other methods of kneading.  Or use Google to search the Web, focusing on videos in particular.

I realize that I may sound evasive.  The point is that there are many different methods for working with your bread.  Some will give you more of what you want for a specific bread, some less. 

If you can, post some pictures of your bread to help illustrate what it is you have achieved and then point out what you would like to change.  That will go a long way toward giving us a common point of reference.

Paul