Hi Michael
Well you can increase no.of schedule report tied up to individual user by altering your upstream parameter Application.Analysis.MaxNumBgReportsAllowedPerUser
But more the number you increase may likely have a chance of getting into performance issue. Before setting up the new value to this MaxNumBgReportsAllowedPerUser Parameter, Better raise Service Request with Ariba Inc and get confirmed about impact
If you need to alter value to this parameter ,Well you need may need have Upstream - Administrator permission-
Manage-Administrator-Parameters- Search for MaxNumBgReportsAllowedPerUser under Partition/None- Set new value.