Hi there
First - thanks for your answer.
I have looked at the " Adaptive layers " option - it did not solve my problem - actually I have not really got the idea of it yet..
Actually I should have added a picture of it - but the problem was weak material due to infil. I found a option "Minimum infil area" that did id - so the area of the weak spot is solid.
Again thanks for your suggestions - and the overlapping thing sounds interesting - I will have it in my mind.