One method which works at times is to use the Appearance Panel and duplicate the strokes with brushes applied. Then using Effect > Distort & Transform > Transform move the duplicate stroke slightly, and possibly tick the Reflect options to alter the "distressing" placement and hide the duplication more. At times adding a slight angle to the effect also helps.
Effects related to one of those duplicates:
Each stroke copy was only moved a small amount. The second and third were reflected in the Effect, necessitating a 1° rotation to prevent large gaps at the ends.
This can essentially provide a thicker stroke appearance without merely scaling the brush artwork.
Note that you could also apply a different brush to the duplicates in the Appearance Panel for more variation if desired.
You can save this as a Graphic Style to be easily reapplied later.
Another option is to create your own brush artwork. You can do that using an existing brush and editing it for the stroke weight appearance you want.
Merely draw a path with the brush you want and set the stroke to the weight you want. Expand, edit the artwork as desired, then create a new brush.
Above, I merely used Object > Expand Appearance on the 5pt stroke. Then used the Eraser Tool to alter the artwork. When finished, I dragged it all back to the Brush Panel and created a new Art Brush. Then merely applied it to a 1pt stroke. This results in the appearance at 1pt being as I want.
In short, you aren't obligated to use Adobe stock library items and many times generating your own library items, even if they are merely edits to Adobe items, can be quicker/easier than trying to "tweak" Adobe stuff to fit your desires/needs.
This is all quick and dirty to show the methodology. And panels are from Illustrator CS6, but it's all essentially the same in newer versions of Illustrator.
