You can get some auto strains to finish faster by shortening the time you feed them veg nutes but you lose out on a lot of vertical growth and that results in reduced yields. They produce best when vegged for 5-6 weeks, then flowered for another 5-6 weeks. Personally I'd rather wait those extra couple of weeks to get 2 oz. off a plant as opposed to 1/2 or 3/4 of an oz. Yes, the advertised short times are somewhat of a sales pitch, but we're seeing more breeders recommending 10-11 weeks on their strains for optimum yields.
When you consider that autos have only been around about 5 years now, it's pretty amazing how far they have come in that relatively short period of time. IMO much more work is being done with autos compared to photos and their popularity is increasing all the time. In another 5 years or so I believe they will dominate the indoor growing market.