Considering that she wants to make up for mistakes of the past (and not merely honoring tradition)
Unlikely in this scenario for three reasons.
Do you think their relationship with the Chantry would survive if they openly admitted they were all touched by a spirit? That's the sort of stuff that dangerously comes close to crossing comfort lines.
Another issue would come from recruitment; how many would willingly sunder their minds for an entire year with no guarantee of success of contacting a spirit.
And finally it would make sense to have the practice kept secret for all those yet initiated to prevent imitation.
How many would see the worth of such knowledge; what could it lead to.
Cassandra is a woman of faith but also one of reality.
There is good reason to prevent that knowledge from going to far.