This self flash covers a lot of angles; it will blind pretty much everyone except those who are being rats and tuck behind blue box, or behind the wall to the right side. Everyone else holding door or camping to the very left will get wrecked. Plus unlike the one where you aim to the corner of the box, this doesn't require a jump throw (which gives away your position)
No strategy or line up is 100% perfect, but I've had good success rate with this.