I concur on the above for short boil on pils malt especially highly modified pilsner malt I probably can't taste DMS raw cabbage corn thing 
.
30 min boil pils
And this beer above I acidentily added about 1kg grain to the kettle without my mash bag lol.
I had to pour all the wort out through my biab bag and decant it back in so alot went wrong but still come out fine .
As for efficiency get your crush right and a good sparge will help for sure.
Or just throw in another handful or two of grain and don't sweat it.
.30 min boil pils
And this beer above I acidentily added about 1kg grain to the kettle without my mash bag lol.
I had to pour all the wort out through my biab bag and decant it back in so alot went wrong but still come out fine .
As for efficiency get your crush right and a good sparge will help for sure.
Or just throw in another handful or two of grain and don't sweat it
.
