This probably indicates that the PCTFREE and/or PCTUSED thresholds are being crossed in different blocks of the same segment simultaneously. This is to be expected if you are doing multithreaded deletes, or something like that. Otherwise, increase the gap between PCTFREE and PCTUSED. Changing the number of FREELISTS will not help.

When I query V$WAITSTAT, segment header shows 1098 waits. Does the output show that there is any contention with the freelists? If so what is the corrective action?