I am brewing today and I've got the mash rest on at the moment. I missed the mash rest temp by 4 degrees c. I didn't think it would matter too much... but almost an hour and I just checked the gravity. It's coming in at 1.050 and I was aiming for 1.065! Miles off and I actually slightly went over my grain bill because there was a bit left in the bag. Not much.. but I'd expect to hit my 1.065 at least? My recipe was calculated with 70% efficiency, but it looks like it's actually a lot less. I've not taken it out of the mash tun yet, the hour buzzer is going as we speak. Should I leave it in the mash tun for longer or will the temp have dropped too much to get anymore sugars out? Also, should I be testing the OG directly from the mash tun? As I think about it, it's not the end of the world as I was aiming for a late 6 early 7 % IPA. So with this rubbish efficiency it might settle at about 5.5-6% which is respectable. That said I would like to get to the bottom of why my efficiency is so bad and I'm missing the OG by so much. Could it be those 4 degrees?