I suggest that we edit the fourth-to-last paragraph of FAQ #148 to include this, since it's where other things of this type seem to go.
Only the 75 most recent entries of your journal will display in the Most Recent view. If you attempt to navigate back further than 75 entries, your journal will begin to use the day view. You can change how many of these 75 entries display on a single page through the customization interface, if you are using S2 (http://www.livejournal.com/customize/), or with the OPT_ITEMS override, if you are using S1 (http://www.livejournal.com/support/faqbrowse.bml?faqid=13). It is only possible to display up to 50 entries on a single page.Something like that?