It is possible to do 2 plates at a time at much less than double the time, especially if you have 2 magnetic plates.
The protocol is best if you need extract DNA from lots of samples, pooled or not.
It should take 5.5 hr once you know what you are doing.
The numbers in gray refer to electronic repetitive pipetting.
The elutions are in larger volumes than 1/4th.
The first step could use less concentrated RNA samples, so that water is not needed. The Qiagen Plant RNA extraction kit elution volume of 60 µl should be sufficient with typical Mimulus leaf extractions.