Tables can be split up into columns while remaining one entity, just like mtext objects. The easiest way to do this is with the light-blue triangular grip at the bottom of the table. (It's the one in the middle of the row pointing upward. The other two re-size the table's rows or columns.)
- Enabled just means that table breaks are turned on. If you set it to No, the table goes back to one big long column.
- Direction (right, left, or down) controls the placement of the additional columns.
- Repeat top/bottom labels controls the display of header rows (so that the extra columns get headings too). See this post for more on that.
- Manual positions lets you decide whether the columns can be moved independently of one another.
- Manual heights lets you decide whether each column can have its own height or whether they should all be the same (although the last one may be shorter).
- Break height is the height of the column (if Manual heights is set to No).
- Spacing is the distance between columns.
With all these options, you should be able to get your long tables to fit in any space you need them to.