6 days a week? any less isn't productive? seriously? For beginners or committed university students, maybe yes, but for most people, I'd take this with a grain of salt.
In my opinion, anything that is regularly scheduled is fine. You can be productive this way as long as its mindfully directed practice. Session duration isn't covered on the list and will affect how frequent you'll need/want to practice. How long can you stay focused and mindful during a single practice? What are your technical goals? How does your gigging schedule affect the content of your practice? do you have gig dependent or time dependent goals that will affect your session duration/frequency? Its a person decision based or what can of progress you want to see, how much time you have, and what your goals and commitments are inside and outside your music.
Everything else, I agree 100%, not trying to be a scrutiny scrooge. Planned, scheduled, and mindful practice is key to progress. "Going through the motions" is no way to practice.
I'd also recommend not doing everything in every session. Especially if you practice many times a week, devoting one day to technique/speed, another to groove/feel, and another to reading/learning/transcribing, for example.. can help you get more done.