One more thing, if the required patch is 108528-24 and the system already have higher versions like 108528-26 and 108528-29. Do still need to apply required patch 108528-24?
And also bear in mind that its recommended to always use the patch cluster instead of applying individual patches. You must know the dependencies if you're updating a patch at a time. But its never recommended.
But in cases where interim patches are released by SUN, you will have to patch using the backout "-B" option.
You don't need to use -B. That option is only for specifying an alternate backout location ( other than package db ) so long as the -d option is not specified a backout directory will be created.