I did 8 turns on my 3's in the field.. I had originally been practicing for 6 but I would sometimes come up a bit short and my coach made me work on the layout for 8 because there are 8 on the diagram (even though the number required is not specified), and it involved making sure those turns were on smaller lobes with more controlled edges.. it worked out fine. When I do them now that I'm no longer working on passing that test I do 6 since I don't care if I fill out the ice or not - if I'm a bit short, it doesn't really matter since I do them as more of a warm up
When I do the double 3's on gold I end up doing 6 lobes, but the rulebook does state 4 to 6 half circles for both of those.
The lobes on the brackets are different because there's some overlap on the pattern when you switch sides... if you were to do the same brackets from one end of the rink to the other only 6 lobes would really fit, but since you loop back and start again for the second set the lobes can be bigger. I've been spending a lot of time on those recently, with lots of discussions about just how far past the red line to go, and ultimately my coach wants the 3rd turn to end on the red line, and the 4th to start on it, which basically has me ending on the blue line and skating back to the other blue line for the other half of the pattern.
My coach and I had LOTS of discussions about the number of lobes for the spirals on silver. I ended up doing 4 because she felt that they were "lopsided" doing 5 (she liked them in pairs), and it was really difficult to fit 6, so we decided I could do 4 since I didn't have a problem doing them that way and I wasn't falling into flats trying to hold the edges longer.