If you're going to finish on grass, my opinion is that there is a huge potential for cutting cost by paying attention to the genetics that do it in a shorter time frame. We calve in late May and June, so ours finish at or near 2 yrs of age. We've had purebred Galloways fat by the time they're 20 months, and we've had some crossbreds do the same. Most do it at 24-26 months, depending on grass conditions for the year.
When ours are on grass as yearlings, anything that's lean and green gets sorted off and sold when we can tell that they just aren't the type to finish on grass. They might as well go to a feedlot where they belong. They're just not the genetics we want. We're getting most of those culled out now, most of which were purebred Angus and one sire group of Galloways.
The right body type though, and it's amazing what you can do just on forage. We have some crossbred steers right now that jiggle when they walk. THey're 2yr olds, Galloway sired and out of Tarentaise cross cows. They're weighing 12-1300lbs, and I don't wanna guess how much they're eating in a day - they're diesel burnin' brutes. Our purebred Galloways will finish @ 11-1200, and yield 60% pretty consistently.