There is no 'storage' in Reno. The two cars in question may have unloaded at Reno and re loaded at Reno the next day. Plenty of tracks in Sparks to toss 2 to more cars...
East of Sparks the double track goes to single track. There is a passing track near Fernly that fits Amtrak perfectly, but nary an Uncle Pete mega train. Those cold mornings in the trench, waiting for 5, it's advertised has come and gone, headlight appears to the east, its a mega merch or grainer, 20 to 40 minutes later 5 comes rolling in. I don't think Uncle worries about time hits much.... Hwival Sips could substantiate that.....