those first few
months of commuting were some of the highest risk riding I ever did.
The first few months of riding are the highest risk riding anybody does - anywhere!
And riding on the freeway now in traffic is still very high risk.
The day I stop being scared is the day I should stop riding to work on a bike.
Riding a motorcycle anywhere is a high risk activity. Full stop! Some of the particular risks may vary from freeway to surface road to...but riding is just plain dangerous. The only way to ride "safely" is to commit to respecting the danger every time we mount up, and commit to constantly learn, improve and stay focused.
I am the noob of whom you speak. All my life on 2-wheels but only a few months on a motorcycle. In the past few months I've logged about 1500 miles on surface roads urban and suburban, freeways both congested and not, and plenty of time on the twisties. Am I a complete idiot? (Don't answer.) Maybe, but I am learning and going out of my way to absorb as much knowledge as I can (books, courses, workshops, and advice of experienced riders. THough the last one can be the most dangerous as evidenced by all the experienced riders on this thread that completely disagree with each other.)
Freeway or not at some point your mind will start thinking about what you want for dinner, or that meeting you have tomorrow morning. It's the human condition. The key is to be aware when you're mind drifts and bring it back to the issue at hand - staying alive.
At least once a week I return to the range where I did my CMSP course to practice the drills. I am fully aware that the drills I do at 15mph will feel entirely different when the SHTF at 70mph, but that is how we develop muscle memory and reflex. If I have to stop and think about my reactions to a situation at any speed I'm screwed. So I need to burn them in. And if you're veteran, however experienced, you should continue to drill as well. What do professionals do when not competing? They practice. They never stop practicing. They're never "good enough." It's great to HAVE experience, but when you start thinking you are experienced is when you get in to trouble.
Riders love to talk about limits. Limits of skills, limits of performance, limits of traction, etc. It's a stupid discussion. Likely only top level professionals have any concept what limits on a bike are. For the rest of us, not just newbies, discovering limits on a bike generally means a trip to the hospital or the morgue. I know my bike is far more capable than I am, so I ride within what I know and try to keep learning incremental. Most importantly, I work like hell to keep my mistakes small. When I ride past a T with a car waiting to turn left in front of me, and only register the potential danger as I'm passing the intersection, I give myself a good hard mental kick in the arse. Absolutely nothing happened, but I missed it nonetheless. I tell myself not to let that happen again. I may not be so lucky the next time. Safe riding is to react as little as possible and proact as much as possible. (Yes, I know that's not a word.)
Finally, after all this verbal vomit, the question itself is entirely flawed. Where a newbie should ride is up to the individual. As a newbie I'm told I shouldn't ride the freeway. I shouldn't ride the twisties. I shouldn't ride during high traffic times. Hell, I guess I shouldn't ride. Sorry brothers and sisters, yes I should if I want to. As long as I respect the danger. The first time I rode Skyline I took the 35 curves at 20-25 and it was scary as hell. Today I'll take them at 35-40 with a big ole grin. But I actually have no desire to take them 55-60+. That is what the track is for. Never the street. I don't give a crap about finding or pushing the limits. I'm having fun and coming home at the end of the ride. I'll lane split on the freeway if traffic is stopped. If traffic is rolling at 30? I'm rolling at 30 too. When the cars stop I advance my man a few pegs. I have no respect for the motorcyclist splitting lanes at 60 when traffic is rolling at 20. And the cagers think we're all a bunch of douche bags cause of the people doing that.
Human beings are used to being at the top of the food chain. On a bike - we're nothing but prey surrounded by big, heavy, gnarly predators. It's ok to enjoy that mouthful of prairie grass, but the minute you forget about that lion lurking behind the tree - you're dead meat.
Be safe. Never stop being a Newbie. Never stop learning.