I believe the answer is all the time and any time but the problem is man is busy most of the time. Man is always on the go and busy on his and her personal business. Most of the time we give God our left over time or desperate time.
It is easy for man to be preoccupied with something other than God. But i believe less time with God gives us more headache, stress, pressure, financial woes, mood swings.
If we give God first place in our lives and do His business then He helps us with our business.
How much time we spent in prayer tells how important He is in our lives.