Apart from riding the same route (in more urban areas there aren't many options located close to homes and offices which don't have too many traffic lights and stop signs, and you really don't want to drive someplace to ride six days a week dealing with rush hour traffic on 5) that's not common.

Riding mostly on the weekends isn't enough for good fitness.

Riding at the same perceived high intensity all the time just leaves you tired and slow, perhaps with health problems. It keeps you from being fresh enough to really work hard, and doesn't allow recovery for your body to adapt to training stress. I get my biggest gains after my rest week (1 in 4 is traditional, although some athletes need 1 in 3 and others can go longer) which stick because they're not just from being fresh.

There are too many variables in things like wind and traffic even when riding the same route for measurements to tell you anything about the progress you can make in a month or even two. People use objective measurements like power (210 Watts is 5% better than 200 even if you are slower due to circumstances beyond your control) or heart rate (which measures a side effect of how hard you're working and doesn't show gains, although it does differentiate between feels hard because you're working hard, feels harder because you're fatigued but can dig deeper, and isn't possible without at least a day of recovery).

As an introduction you might like The Time-Crunched Cyclist: Fit, Fast, Powerful in 6 Hours a Week which is built around low-volume training and has complete plans you can follow as-is. Friel's bible is more of a do-it-yourself exercise with some assembly required.

More time will produce better fitness - you'll get more of your energy at endurance paces from fat preserving your glycogen for hard efforts, and your peak will last longer. If you go that route you'll want to spend more time at lower intensities and not base what you do on the Time Crunched Cyclist.