Blob brush annoying behaviour

[Sorontar]

I want blob brush to merge to areas of same color. It only merges when there is nothing visible between existing are and new blob. For example i cannot fill the white gaps with blob brush so that all gray would be joined to be one area, only because black is above gray. Why would i want new area there and not them joined. When is current behaviour useful. Joining areas together takes way too much time.

[Monika Gause]

So essentially you want to fill the area between those 2 strokes with grey? Or even with black?

The shapebuilder tool should do that.