Gehna: Hopefully this info can help you. I can't directly answer your question, but the following websites give insight into your questions:
This confirms your "3 day" comment: "A single dose of Diflucan remains in the tissue at effective levels for 3 days fighting the infection."
This confirms that Diflucan can be effective when taken at something other than daily intervals: "Diflucan works best when the amount of medicine in your body is kept at a constant level. Do this by taking Diflucan at evenly spaced intervals. Take Diflucan as directed since different conditions require different methods of use. Diflucan is usually taken once daily. Another Diflucan dosing method involves taking Diflucan for one week per month until treatment is completed."
This confirms the USUAL dose and duration: "For treatment of systemic candidiasis: The usual dose is 200 - 400mg taken orally once a day for a minimum of 4 weeks and at least 2 weeks after the disappearance of symptoms."
This confirms that doses can be lowered, but still potentially be effective for some people, although 25 mg seems low..? "Your dose may need to be reduced if you have kidney problems."
This confirms that people with special needs (specifically, renal insufficiency) can take doses spread apart as much as 3 days (72 hours): "Patients with renal insufficiency:...However, when treatment for patients with renal problems consists of two doses, the normal dose can be administered on the first and second day of therapy. After this, the interval between one dose and the next is modified based on the creatine clearance: Interval between doses (24, 48, or 72 hours)."
So...yes, Diflucan will stay in your system for 3 days...and one can potentially take less than the usual 200+ mg dose and still see results....and one can potentially go as long as 72 hrs between doses if necessary. I'm not a doctor, but I would think your idea may have merit, although once again, 25 mg seems low..? I have some Fluconazole (generic Diflucan) I can sell you very cheap, my personal supply I no longer have need for (see my post on page 10 of this forum). BEST WISHES ON YOUR RECOVERY, GEHNA!