Why do you people hate Last Friday Night? Comparing it to This Is How We Do.
The ONLY comparison between the two are "Wow, Katy really failed to recreate Last Friday Night with the mess that is This Is how We Do, didn't she?" - The shout outs alone should be enough to put an end to discussion of it being a single.
This Is How We Do is the Peacock of Prism - Everyone wants it to be a single, but Katy and Capitol are smart enough to realise it'd be career suicide and so keep it as an album track.
