I (not OP) would say 2-3 years minimum. If an employer doesn't have enough varied work for you to tackle and learn during that time then maybe less. One perspective is long enough to get a promotion.

As a hiring manager, I would generally exclude, from the 2-3yr min concept, roles like consultancy/freelance or circumstances beyond the candidates power to avoid (layoffs, acquisitions, etc.)

I don't see it as a hard rule to follow, just something to ask about if there are like three 1 year stints at different places in same town.