Also need to look at what is in open time now vs later in your RES period. Typically they need more RES over weekends/holidays than during the week. CS also has knowledge of white slips and yellow slips. They might know that they are hurting for RES today but in 3 days they're covered with WS, OOBWS, and YS so they choose to delay rest. Or they are just effing it away, but I've found that when it comes to covering the schedule CS usually figures out the most efficient way of handling their reserves.