The question to ask: what is the potential benefit to performance. How is this outweighed by the potential negatives.
So say that a normal trainig cycle nets you 0.25% improvement but with only 1% risk of injury and no risk of burnout.
Say a crash cycle nets you 0.75% improvement but with a 5% injury risk and 5% rksk of burnout.
Is what you gained potentially worth what you’re risking. Because an injury can end a season, burnout a career.
Note: numbers are made up for illustration purposes.