Our 2006 Corolla, which lived a hard life of teenage drivers, before being gifted to one of our children, got a simple D&F roughly every other oil change. I changed the oil on that car every 5,000 miles, using whatever 5W30 was on sale, so the D&F was every 10-15,000 miles.
The car was given to a needy family two years ago, with 240,000 miles on it, running and shifting perfectly. The paint was tired, headlights faded, and the wheel covers were long gone, but it ran perfectly. So, our D&F was enough to keep it running.
I used T-IV but Maxlife at the time claimed to meet T-IV and was the same viscosity. Newer Maxlife meets the Low Viscosity requirements, so, I don't see how it can meet the T-IV spec. T-IV is relatively cheap at the Toyota dealer (and I used to buy it by the case, as that's what I used in the Volvo transmissions that also required T-IV), and you're only buying 4 quarts at a time. I think I would stick with a JWS-3309/T-IV fluid, not a universal LV fluid.