I think at 99 the final final magian staff trials should be compactable, provided you have finished all of the staves involved up to the final level. It can even be a magian trial itself!
The staves would all have to be of the same element and all 100% finished, but I think being able to combine the staves based on element would help with inventory tremendously. Instead of 25 staves, we'd be back at 8.