Well, for the sake of argument, let's say the average person uses 2-3 teaspoons a day. They may use a teaspoon more often than that, but the one they use for tea will usually just be rinsed under the tap and reused, so it only really counts as one teaspoon. Then there's the one they use for creme fraiche and the one they use for chocolate sprinkles. You don't always have chocolate sprinkles with your creme fraiche, so that where I got the 2-3 from.
Now, no one wants to do the washing up each day, so let's say you wash up once every three days. So that's 18-27 teaspoons. 18 teaspoons is the MINIMUM, 27 is optimum. So that puts too many teaspoons somewhere in the range of 30-32 teaspoons. Excessive is usually at least two more than too many, so greater than or equal to 34 teaspoons is an excessive amount of teaspoons for a household of three people.