I keep all my browsing history. Frequently I have the question "how did I stumble upon site X?". I can go back through my history and see, aha, that I visited site Y just before my first visit to X. This is handy because site Y may be a site with a lot of useful links like X. However, if I now visit site Y again, the history list removes that past entry of site Y and keeps only my current visit. This breaks the connection between X and Y. Any time in the future I want to find how I got to site X, I'll be stymied. The more useful links which site Y has, the more likely it is (in the current Firefox) that I'll lose my ability to find it by that sort of history search: each time I visit site Y, all previous connections are lost.
I would like a checkbox for "please have browsing history keep every visit to a page". This would help me on a near-daily basis.