You don’t have to do all zone2 
She did start in an untrained state. Not a lot of riding for tangible #gainz
Posted my longitudinal / long-term results in another thread, re-posting here:
| Year | Total Hours | % easy riding | Easy Aerobic Power | FTP | VO2max “Aerobic Ceiling” |
|---|---|---|---|---|---|
| 2021 | 350 hours | 80% | 170W | 265W | 4003 ml/min |
| 2022 | 400 | 80% | 190 | 270 | 4146 ml/min |
| 2023 | 350 | 87% | 200 | 275 | 4226 ml/min |
During those years I went from late fifties to early sixties, these are the years that your vo2max is suppose to be declining 
and working stiffs like me are jealously seeing retired friends do epic adventures around the world