RRA's steps and rows setup

[arim]

I am confused with the RRA's setup:

Every RRA stores data for a little more than the double of the tittle says.
i.e the first one stores one value every RRD Step (steps=1) and keeps 600 values (rows=600). Now because our Step is 300 seconds this RRA keeps data for 50 hours and the title say it is Daily...

Just reading the RRDCreate doc. I would set Steps=1 and Rows=288 for a Daily 5 min.av. RRA

what I am missing?

thanks in advance!