We recommend a minimum of 20-30 minutes per day; an hour or more is even better.
One cannot be too grounded and you can’t overdo it. It would be ideal to be grounded 24/7, but it is not realistic. Set a grounding goal to ground for 1-2 hours a day with 20-30 minutes a day as the recommended minimum.
The longer you ground the more you may feel the difference, physically, mentally and emotionally.