Depends! Many cookie cutter plans followed a traditional 3-5 week build, 1 week recovery because they don’t have any ability to judge what your starting fitness level. Since Xert knows exactly where you’re coming from, it’s easier for the system to judge how much training you need, because it’s relative to where you are now.
With a sufficiently low improvement rate, it’s possible to train for weeks on end without a dedicated recovery week, since you never dig yourself into a deep enough hole to require additional recovery time. However, the opposite case is what @wescaine mentioned… if you dig yourself into a deep hole, you’ll need to take time off in order to freshen up, before resuming training. For most people, the sweet spot is somewhere in-between those extremes. You still can follow a 3W / 1W improve/recover schedule, if you’d like. You can also try block periodization (1W of extreme-2 / 3W of recovery). Xert is very flexible, but does require a little bit of input from the user.