When the difficulty has left the sport. Mentoring works on performance under pressure. If mood, sleep, eating or friendships have changed, that needs a clinician.
Work out first whether this is a difference of opinion or a welfare concern. The two need completely different responses and they get conflated constantly.
Ask what they would do with a completely free Saturday. Someone doing it for themselves answers immediately. Someone doing it for you watches your face first.
The biggest structural advantage available to a young cricketer in either country, and the fastest way to burn one out. The difference is a block, not a second season.