There's really no such thing as too long, unless someone else gets
to market with the same thing first.... and there's no way to predict that. 

Only a few of the merchants make enough money to count it on the
basis of wages.   The rest of us are working mainly for the love of the craft,
with money as a nice little 'tip'.

Unless you're one of the few high-volume producers, you'll be happier
in the end when you satisfy your sense of artistic integrity.

And your customers will be happier with high quality.

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