Lets get In-geom ability to extend it's active time

All we know that an In-geom is good for packs of goblins and for fast rifts too, where you can kills elite packs like a bubbles. But what if In-geom can extend it’s bonuse time when you kill a few packs or goblins at the same time? This can change the game experience and may be meta for speed-grifts, who knows… Also who play solo will give a choice for GR. If player can kills packs fast - he choose an In-geom, if not - something else.