As a primarily Vinyasa practitioner, I'm a big fan of the variety. I like coming to class not knowing what awaits me, and I love when it happens to be either exactly what I want or exactly what I need. (Often the two are not necessarily the same thing) Variety is also how you learn new things - crazy new arm balances, new mudras for meditation, or even just a new variation on a standard pose. I've been taught trikonasana so many different ways by different teachers. It all winds up looking like essentially the same pose, but there are different ideas about the position of the hips, whether the hand should be on the inside or outside of the front leg if it's touching the floor, where the gaze should be, how revolved the upper body is or isn't toward the ceiling...Tiny little changes always challenge the way I think a pose should be and teach that there's no Yoga Police ready to charge in and tell you you're teaching it wrong.
I also appreciate the variety because, as almost every fitness expert will tell you, switching up your routine is key for avoiding a plateau in weight loss (if that's your goal) and keeping your routine the same every day will eventually cause it to lose its effectiveness. Also, doing the exact same thing every day could potentially cause harmful wear and tear or overuse of certain joints.
All of that being said - there are pros to keeping a consistent routine. If we're just talking about a simple, on-your-own home practice, it's a beautiful way to keep a solid, grounded anchor for yourself throughout your sure to be hectic, ever-changing life. It's a way to come back, check in with yourself, and find some comfort in the reliable consistency.
As for practices like Bikram (and Ashtanga, and any other school that advocates a set sequence), the instructors claim the same benefit as well as the benefit of being able to see immediately your progress - or plateaus, for that matter. There's certainly something rewarding about working towards a pose for ages and then one day just slipping into the full expression of it.
The mental aspect of consistency vs. variety is a little less easy to define, I think. For you, personally, would your mind wander more doing the same thing day in and day out, or would that actually help you to keep a steadier focus? It's a little bit of both for me. I find in a Vinyasa class, I've got to keep my mind in the room because I have no idea what's going to be thrown at me - and maybe this teacher is going to ask for my hips to be parallel instead of angled in trikonasana, so I better pay attention.
In Bikram, however, they often say "Don't think, just do." (My teachers have, anyway) They don't mean don't use your intellect or listen to your body, they just mean don't let your mind chatter get in the way and distract you. There's a strange focus that comes from not having to think about what comes next. You know you're in the room, you know what you're in for, you know exactly the 26 poses coming your way - you just have to focus on doing them as best you can. I've experienced classes these last 3 weeks where that's really worked for me and kept me super present and engaged in what I'm doing, and also days where my mind has wandered far, far away to try to escape from the hot little "torture chamber" (Bikram's words, not mine!)
Thinking about this debate always brings me to my beautiful best friend, Kendra Cox. We met in college and I always admired what a dedicated runner and cyclist she was. She was super athletic and never struck me as the type who would be into yoga (although heaven knew her tight muscles could use it!)
Kendra and I tackling Toe StandSince college, and since life has taken us both in unpredictable directions, she discovered Bikram yoga. Kendra would be perfectly happy to live her entire life in 100-degree temperatures, so I figured it was a match made in yoga heaven. However, she emailed me one day absolutely bored to tears with the sequence and wanted to know when the heck they were going to get to crow and Chaturanga. The athlete in her, while probably drawn to a lot of the hardcore aspects of Bikram, needed more challenge and strength. I recommended she find a heated vinyasa class to marry her two loves of heat and vareity. She discovered Baptiste Power Yoga and has never looked back. (I'm sorry to say I've never taken a Baptiste class...gotta put that on my list!)
Something she said that also always struck me as funny, that I kind of disagree with her on, is that she found it absurd for people to tell their Bikram teacher, "That was a great class," when it was just the same thing every time. Despite the physical asana being the same, I think finding a good teacher (and a "great class") in Bikram is even more important than in Vinyasa. Because you're doing the same poses over and over, the challenge to the Bikram teacher is unique. There will be different qualities that keep students coming back to your classes - a high of motivation, positivity, and humor are three things that will keep me faithfully returning.
I've found my few teachers I love at Bikram Yoga NYC, as I mentioned, and I accidentally discovered another yesterday - a new-to-NYC teacher auditioning to work at the studio. A little more variety was forced upon me as I tried to cling to the consistency of the teachers I feel safe with, and surprise surprise - I loved it.