Over the years, one of the most informative items that I learned about modern professional cyclists was that during the off-season from mid-fall to late-winter they worked to stay within 5% of peak fitness.
This meant that when the season ended, they didn't stop training entirely, but rather dialed back the intensity of their workouts slightly. Their rides favored longer, slower efforts in order to maintain not only a base level of fitness, but to also give their bodies and minds a rest. This approach enabled them to quickly shift back into general racing shape at the end of winter.
There was a point in time where it was fashionable to step off the bike completely for a few months. This often led to weight gain, loss of fitness, and an increase in the amount of effort to regain any lost fitness.
The theory is that the closer you are to operating at 100%, the less energy you need to spend in order to return to maximum efficiency and effectiveness. There's also less stress on the system, your body, as you make this shift.
The work required to move from 95% to 100% is different than moving from, say, 50% or 75% to 100%. The start up cost is far higher when you have a larger gap to overcome.