"Always allow WiFi roam scans " - is it of any help to end user? Screenshot ( at bottom ) shows the option in Developer Options. It reads



Is it of any use for end users to activate it? 

Description leads me to guess it might be useful when you are on the edge of WiFi coverage zone , switching to another WiFi may be faster

Edit: Googling threw up results confirming my guess on posts like this ( few more on similar lines). However, would request more explanation, since this is not encountered commonly as a suggestion to counter WiFi drops
enabling it will automatically connect to the best wifi around with best signal strength and best speedbut it also effects your battery life