Depends on the situation.
We usually have a 'planning' session of about 5 or so minutes per side, with each side getting a look at the table while the other side is upstairs. Whether we follow the plan or not is another story…
However, planning is more important when you run multiple tables -- you may see one of your side's commanders over at the other table, but you can't see what exactly is happening on the tabletop. You hope he's sticking to the plan, but you never know…
For a look at multiplayer, multi-table gaming, here's a link to Peter's marvelous blog BlundersontheDanube and the Snappy Nappy 'Campaigns in a Day' page.
Snappy Nappy Campaigns in a Day
That will bring you to a set of links of all the Snappy Nappy 'Campaigns in a Day' we've run up at The Portal in Manchester, CT (outside Hartford). Last one (1809 Italy-Austria theater) had 16 players and 17 tables. Maps, umpire and player recaps, etc.
Others include Russia 1807, Waterloo 1815, 1813 Germany (Autumn), and 1809 Bavaria.
Blog also contains the SN Quick Reference Sheets.
Those in the area interested in this big multi-table approach can stop in Sunday April 29, 10am-5pm, at The Portal, for our 5th SnapCon. Peter's running another Snappy Nappy campaign, this one in Spain. No fees or charges. Free Parking.
Full disclosure: I wrote Snappy Nappy.