I don't know the details of your case, nor would I comment on any specifics if you gave them, but I will say that I have done more SRPs than most people on here and I have never completed 2 quads in less than an hour. 90-120 minutes is standard for 2 full quads.
There are two codes that we use to bill SRP: 4341 and 4342. 4342 is used for SRP on 1-3 teeth in a quad. 4341 is for 4 or more teeth. I used to work at a practice where each code was billed at the same amount (which I thought was unfair but insurance paid). The practice I am at now charges half the amount for 4342s as for 4341s. If you were classified as a 4342 I could see how it might have taken half the time.
Also, don't blame the hygienist for your treatment plan. She is neither trained nor licensed to diagnose, that is the dentist's job (even though every RDH I know, including myself, is expected to do so).