Base building for myself and most of the athletes I work with is much more traditional than what you see being “popular” these days, but it’s not completely traditional in the sense of only Zone2 progressing duration unless the athlete has lots of time.
Most of the athletes I work with (myself included) have about 8-12 hours to train each week. Within this range, I like to start off with a prep phase of pure Z2, then I progress into a base phase where throughout the entire base phase we go from having 1 “sweet-spot” workout per week all the way to 2-3 threshold workouts by the end of the base phase. Most of these phases last 3-4+ months, but of course it’s very individual (some respond better to more z2, others better to slightly more intensity). Progressive overload is very similar throughout the phase. We are progressing time not power, so for example I might start the SweetSpot at say 2x20, then progress to a 3x15, then a 1x45, then a 3 x 20, 2x30 etc. Same goes for Threshold (progressing time and TTE rather than trying to push that number higher). For zone2 riding I like to see overloading of about 30mins extra per week on the longer ride. So if the longest ride of the week starts at 1hr, the next week would be 1.5, then 2 → 2.5, until we are at a sustainable level where we will stay as the intensity increases.
Experience is a big component… Some athletes have 10+ years of training under their belts, but still have limited time. In my opinion and from what I’ve see is there is only so much that more z2 will get them with limited time, so we add a little bit more lower-end intensity.
Others are much more new to the sport, where almost anything will see improvements, so we don’t do much intensity (if at all) and just progressively overload the z2 rides.
So to answer the question… yes… kind of traditional base especially compared to the base training you see nowadays with way too much intensity. However, that’s not to say I don’t do a lot of Zone 2 riding or riding around 1.3-1.8mmol/La. This is extremely important to manage fatigue and get the adaptations needed for a long season ahead.
One other thing is that I do much more realistic and longer FTP tests, so I don’t run the risk of overestimating FTP. I find a lot of people overestimate their FTP, which makes it even worse when they are doing higher intensity base training.
I really liked this podcast episode from a very experienced coach titled “What is base really?”. I feel it fits well with what I’ve seen personally