I could not find the post from the mom of two who is a pharmacy student to reply to her.
My husband is a pharmacist with over 25 years hospital experience. he never questioned the doctors assumption that it would take 6 weeks to totally be out of his system. all drugs have some residual and cumulative or residual effects. it really isn't magically gone from your system in a set number of hours. especially a daily dose and more so in the elderly, and I have seen this first hand , when they are dehydrated or other wise compromised the drugs can stay in their system for a time and accumulate.
i will update on our son later today, he is doing much better two weeks off