This. If you look at my post, Cost -1 Belinda will take you 41 hours worth of stamina regeneration on average. That's just Saturday and Sunday, where you don't conflict with dailies (other than Saturday's Orb daily) and you'll have a -1 cost, same as if you pulled the same premium unit twice.
Cost -2 would take 116 hours/24 = almost 5 days but you can still take Monday and Thursday dailies and have an almost min-costed Belinda. It only gets ridiculous if you just HAVE to have that final CR.