Because I take a special interest in submissions to the site, especially reducing the clutter of bad and incomplete pages, I offer this in hopes that it will help members. The FAQ's have been updated to reflect this.
At the very minimum, this is the definition of a complete mountain page (and the general idea transfers to routes, areas, and canyons as well):
There is an overview telling us something about the peak, preferably what makes it worth climbing.
There are good enough directions so that with the page and a good map, the user can get to the mountain without needing any other resource.
There is route information telling about length, difficulty, and elevation gain. There should be details about exposure, rock quality, tricky or dangerous spots, etc. as appropriate. If the route information is not on the main page, it is on an attached route page.
There is at least a primary image (an amazing number lack one or any pictures at all).
There should be information on camping and red tape, even if just to tell us that there is no camping or red tape.
This makes a complete page, not necessarily a good page. There are many mediocre "complete" pages, and they often become candidates for adoption.
If a page is submitted and is not complete after one full calendar day, it may be deleted or changed to a custom object; in the latter case, you can continue to work on the page at your own pace and, when finished, change back to the desired object type or copy/paste to resubmit it as a brand-new page.
So to be clear: if you submit on October 1, the page may be deleted or changed if it is not complete by October 3. It does not mean this will happen, just that it can. There may be cases where staff members make exceptions, such as if a member with an established record of excellent pages is working on a big project and needs more time. In general, those with a record of submitting good pages will get more leeway, though not indefinite leeway, and their pages are far less likely to be changed or deleted.
Although it is not a formal rule on SummitPost, many agree that if you haven't climbed it, you shouldn't post it. There are a few understandable exceptions, but they are very few. If you haven't climbed the mountain or the route, please don't submit a page for it. If you have not been to the area and do not have much firsthand experience with and knowledge of it, please don't make an area/range page. Share your knowledge and experience, not your research.
While this technically applies to any page type, the chief concern is with mountains, areas, and routes, which are the meat and potatoes of SummitPost. Trip reports and canyons matter as well, but to a lesser degree.
Likely Question: How can I avoid having my page deleted or changed?
Answer: Make sure your work is complete when you submit it, including the attachment and placement of pictures. Most top contributors to the site do exactly this or finish a page within an hour or two.
Do your work offline. Add your pictures beforehand. Then put it all together.
Not good enough? Need to see your work as you do it? I like to do that, too. So create a custom object and use it as a layout page. You can add all your pictures and do all your text and layout at your own pace. When finished, create a new object and just copy/paste your work. Yes, you will have to reattach pictures to the gallery, but that is a small price to pay to be considerate to other members and to make sure that SP's climbing-related content, its core value and purpose, looks as good as it can to the thousands of members and non-members using the site.
Another Likely Question: Why does this matter?
SP is the top mountaineering site on the Web in terms of hits, users, and amount of information. We want to see SP have a solid reputation and continue to grow. When visitors find bad information here, they may be less likely to contribute themselves, visit again, and spread the good word about SP to others. This is why it matters.