Various papers and professionals suggest that beginner lifters benefit from limiting their training. One session of training seems to be optimal for rookies, and anything more actually slows them down. But as they develop, one session of training stops being able to produce any type of improvement and adding more sessions stops being detrimental and actually becomes beneficial—even essential. It seems as though most athletes stop progressing at some point if they don't increase their volume considerably, almost to unbearable levels.
A late intermediate might benefit from training 3 or 4 times a week. And we have elite athletes who train as a profession, thereby spending considerably more time than that. Olympic Champion Shi Zhiyong trains 8 times a week for 3 hours each session! Similarly, Norwegian powerlifting champions train 6 times a week, and many Italian calisthenics champions train for over 5 hours a day.
If someone goes headstrong into a new programme with a higher frequency and more hours of training without being ready, they would only degrade and step back, thereby losing strength. Conversely, if they played it safe, they would only waste time on the same training programme, which would have become useless to them.
So if one wanted to maximise their training and waste no time trying to figure out if they were ready or not to change training frequency, how should they judge if they are a beginner or not?