Depends on your diet, natural recovery abilities, training volume...
When offseason, I can train every day, usually a 4 day rotation for several weeks without a break so long as I'm eating well. Prep mode is different, as the stress on your body from getting less nutrients than your body wants starts you off in a different place than if your needs are being met.
In the past, I've actually done 7 days a week, with a 6 day split (2 leg sessions), and made gains. At my age, it speaks to the importance of diet to support your training.