Been using reversed wedges on most of the vases that I have been doing, usually with small central angle on wedge. Made a new wedge to cut 9 sided object(ring). All my wedges are right angle triangles so the other angle on this wedge was 50 degrees. Here is what I found using it.
Make seven wedges cut at 50 degrees, 10 degrees short, add 10. No reverse.

Added10.jpg Test piece

Add a second 50 degree wedge (8 total). You now have 390. So take away 40 by adding reversed two 15 degree wedges and one 10 degree.

ThreeR.jpg Test piece 2

Add two more 50 degree wedges, making total of 10 and a 500 degree ring. Need to reduces by 140. Found two solutions. 10 -15 degree wedges reversed and one 10 degree inserted normally.

Fin10-11.jpg Top of actual finished vase


Or 10 50, 8 15 and 2 10. (Unfinished vase,)
Rw8-2.jpg Top of actual unfinished vase