You can't believe how much fuel i went through during my inaugural (and only, thus far) cook--an 8 1/2 lb brisket, joined later on by 4 racks of ribs. Of course the temps were below freezing in DC that night, with lots of snow and ice on the ground, and it was fairly windy. I went through an entire bag of Kingsford (the 20 lb bag? not the wee little one). Heck, maybe that's normal. I'm sure it's covered here on the site in numerous places, I'll have to look around a bit more.
I do have a silver bullet cover, but my maverick thermometer instructions said it would be unhappy living under a cover, so I bravely cooked without the shiny silver fellow. (shoulda worn it myself---it was freezing out! lol. Plus it's cool---looks like an astronaut's suit.). If it's windy next time, i might break out the cover, but i sure hate to give up that great thermometer.
I'd gently nudge the coals when the temps started falling, and that helped much, but when they seemed beyond redemption I'd add 1/2 chimney full of lit, plus throw on some unlit coals for good measure. The first time I refueled I added a full chimney. My goodness, you should have seen that temperature spike!
With only one cook to my name, I know I have lots and lots to learn, but this forum is sooooo great and so helpful in speeding up the learning curve. Thanks to all who post here---you can't believe how helpful this is to novices like me.