True, but also pay attention to total costs. UT does charge slightly higher than gate admission for their 1 and 2 day tickets (they state that right on the website), BUT if you want your tickets in advance and are planning on ordering from Disney, watch out for shipping. That is actually the root of my comment above.
About 4 years ago now my SIL and her 2 boys were joining us for a couple of days at Disney. I bought our family tickets at UT, but couldn't get her 2 day passes from UT back then. So I ordered them from Disney and was shocked to have a shipping charge of somewhere around US$25-30! So, yes, cheaper to wait until day of and buy them at the gate, but that slows you down. If you want tickets in hand in advance, UT is still a good option for 1 or 2 day tickets.