Although the system can extrapolate reasonable estimates for rows added because statistics were last collected, statistics that are far out of date (stale) may be worse for Optimizer query planning than having no statistics at all.
Recommendation: Use the THRESHOLD option for COLLECT STATISTICS, so the system automatically determines if statistics are stale and need to be recollected or if recollection can be skipped. See Skipping Unneeded Statistics Recollection with the THRESHOLD Option.
If you do not want to recollect stale statistics because of resource contention, you can temporarily drop the statistics using the DROP STATISTICS command, and use the default statistics automatically collected by the system. However, recollect new statistics at the earliest opportunity.