Only one LO per 24 hours (I think that is the time period. The admins can better inform you as to the specifics.) shows up in the main gallery. I am assuming that is done so that the main gallery would not be overwhelmed by just one person's LOs. I read once in the forums that someone posted over 30 LOs in one day!
God Bless that person! LOL!!! What I do if I post more than one LO in a day, especially if it is a two page LO, is I mention in the LOs that this LO is page 1 of 2, or whatever, or if the LOs are not related, I just mention that I have posted other LOs too. This way people are informed and they can choose to look at the others or not. Sometimes if it is a two page LO where I want people to get a sense of what the two pages look like together I post three LOs. One is a LO of both pages together, which always is small due to file size limitations, and then I post each page individually, so people can look at the details if they want to since that pic is larger.
Just be aware that when you post more than one LO at the same time, the first LO that you upload is the last one seen in the series on your personal gallery and only the last LO is the one seen in the main gallery.
HTH!