I went through nearly half a day's Soylent once without realizing I forgot to add the oil bottle (I was about to pour my second glass and was like "whoops"), so that's not unheard of. I don't think I noticed because of any flavor/texture difference (which surprised me!), I just saw the bottle set aside and remembered I was going to add it in the morning.
One difference I've noticed with 1.3 is that I can shake up my Soylent and add the oil immediately (it seems to be a finer powder?), whereas with 1.0 I would always let the powder and water sit for a few hours or usually overnight before adding the oil.
As an aside, I do always count the pouches as I unpack each box, but that's just the type of person I am. I would be shocked if I ever received less or more than seven pouches per box!