I agree with you to an extent. However, it is possible to get proficient from zero to average (junior Data engineer) in 3 months. I have done it in the past. I learnt databricks in a month while still working my fulltime job and cracked the interview. The goal is not be expert but to be proficient enough to be a useful employee at the company. Dedicating 5 hrs a day to studying these material can do wonders.