SWIM has never taken them more than a few times in 1 week, usually only once a week so he can't really comment on that. However according to several medical books which talk about using doses of 1500 micrograms or less of hyoscyamine, they state that the effects last only 4 hours.

I believe what you're talking about here applies only to doses larger than 1500 micrograms. Large doses slow down digestion considerably allowing the drug to stay in the body much longer than 4 hours. So I really don't think that's a concern when using 10 seeds or less. But possibly it is.

Has anyone taken 1 seed every day for a week before?

What about hyoscyamine motion sickness pills? Do they state that as being a problem on the bottle of pills because I've never heard of that being an issue with normal doses.