How to stop brush with low opacity to build up/overlap

I use a 50%~ opacity brush. But I really hate the buildup/overlap after putting another stroke.(As seen on the right). How do I edit the brush so that even if i paint over, the same opacity remains.
I found a similar problem that was solved.
Unfortunately, that way is unsatisfactory as I have to draw with full opacity first before lowering the layers opacity and thats not really quick and fast. So does anyone know an alternative method?
