For sure, direct sunlight is the most-reliable approach to getting a good IR shot. I have only one counterexample and while most of the image is in the subtlety of the shade, there are still treetops in full sun there.
I don't generally go out with the IR film unless it's Sunny-16 conditions. I have a sneaking suspicion I should try it but I don't have an IR meter and want to get the most from my few remaining rolls of IR820 in a way that I know is reliable. Maybe once I get that 70mm roll of Rollei 400...
I'd say you got good results. The problem with IR (er, one of the problems) is to visualize what happens with infrared film and an IR filter. Blue (sky) comes out pretty much black; green, if maybe green paint, could go pretty black. White objects and green foliage in sunlight come out pretty white; the "Wood effect" with trees looking like cotton candy. Black still comes out black. My general impression is the effective scene brightness ratio with IR is often much wider than the visual appearance would lead one to expect. I had one scene involving a river and woods on either side where the water in the foreground acted as a total sink for IR -- I shot the scene on two different days and still even massive exposure increases produced little detail in the dark (but rippled) water.
I generally bracket a stop or two either side of my measured "optimum" and assume the percentage of "keepers" will be low!
(But it's great when it works.)