I use coupons, but not "extreme." I can get some extremely good deals sometimes, and once in awhile a coupon will come along that I will buy mutiples of from a clipping service, I actually just ordered Sabra and Staceys coupons, but paying 10 cents for something that will save me $1.00 (so technically just 90 cents after cost,) is still a good deal. But I usually only get no more then two papers a week, and I find that to be plenty.
I don't get the people on Extreme Couponing and keep hundreds of bottles of random stuff they will never use, I keep at maximum two or three bottles of things like mustard, salad dressing, different varieties of pasta, etc, and that's even with getting them for free.
I would say I spend no more then an hour a week clipping coupons and making my lists. I also shop at only two stores. All the stores have similar sales, and if it's not on sale at one of my stores this week, it'll be on sale next week, or at least before the coupon expires.
Also, don't believe most of the deals you see if you watch the show, a lot of stores would not allow you to get overage for items. I don't know of a single store that will give you cash back if your total is a negative amount. But there are catalina (the coupons that print at the registers,) deals sometimes, that let me get something for cheap or free with a coupon, and then I get more money off my next order then I spent on that order. I did this with granola bars a couple weeks ago, they were on sale for $2.50, I had a 75 cent coupon that doubled, making each box $1, but for every four boxes I bought, I got catalina coupons for $5 off my next order, and I only spent $4 on the four boxes, so I "made" $1 profit, and I could put that towards something I don't see many coupons for, like fruit. (Though there are produce coupons and deals out there.)
I also won't get something I won't eat. Even if it's only ten cents, and I'm saving $2. I'm not saving anything if it's costing me ten cents and I have no use for it. I will get stuff I won't use if I can get it for free, or if it's a money maker, like the granola bars, and donate them, or if I get too many of one item, I'll donate the extra. There are some deals I "must buy" so many of one item to get the deal, and living alone, I just don't need that much food, but it's cheaper to get more.
It takes awhile to really get good at it, and I even had years of working at a grocery store to help me, and let me figure out every deal that was going on, and I'm still learning.