We understand your concern for leaving a gap between suppositories.
The ingredients of a suppository may last over 7 days after insertion. The reason is that the vaginal tract is a "dead end" of a one-way street. This is different from taking a pill orally through the digestive system.
If you ingest a pill, it may not last more than 1 day. The ingested pill goes through the stomach and intestines and is either digested and absorbed by the digestive system or excreted through bowel movement .
But in the vagina, there is no digestion. The ingredients will stay until they are fully absorbed or flushed out by discharge. Older women have less discharges, especially after menopause due to reduced vaginal secretion. Thus, a suppository will last longer after insertion in an older woman than a younger one. In either case, it may last a week, although the concentration may be reduced toward to the end of the week.
Putting down a big fire may need many fire extinguishers and even a fire engine. But preventing a fire, you only need one extinguisher per household. This analogy suggests that you need a higher dose and more frequent use of a treatment product to clear an active infection, but for stopping an infection from coming back after it is cleared, using one suppository a week may be enough.