It would be a good idea if some of the guaranteed time were used for projects not likely to be awarded by peer review. It was noted that historically it has been difficult to get large blocks of observing time through peer review. Several alternate ways of handling the guaranteed time were suggested. Some of these systems have actually been used in other missions. Time is guaranteed, but targets are not.
All targets are subject to proposal and peer review.
The GTOs would then pick other targets to fill their time. GTOs pick targets not for the entire AXAF mission but for the first 6 months or one year. The remaining time is then awarded to GOs through the usual process. The GTOs then pick targets for subsequent observing periods. Some combination of the above.