Hello, I had the same problem, that my true retention has been lower than my desired retention. So, I simply started to increase the desired retention:
- Increase the desired retention by 1 % and reschedule cards on change.
- Revise the backlog. Study for one or two weeks to see your current true retention.
- Repeat points one and two until you are satisfied with the true retention.
I have aimed to 90 %. My actual desired retention setting is 94 % while my true retention is about 90 %. This state is stable and it has been working for several months. It is an interesting thing my workload didn’t significantly increased and now, after some time, the workload is more or less the same as before the changes.
You can see my original post here: Trying to reach retention 90 %