Once in a while, you get the cell body (or other, large structures). These are always full of noisy patches, most of them just 1 or 2 pixels wide. A larger cursor, i.e. 2x2 of 3x3 pixels would reduce the amount of time you need to paint the entire body, without reducing the accuracy. In fact, accuracy might even improve.
It does not have to be a fancy photoshop-like paint tool, just a larger cursor you could turn on by pressing a key (just like shift).
