Are most people playing the "recommended" basing.
Meaning 15mm 1 base is 8 figures 2 deep four wide for foot?
How about for 25mm?
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I can't speak for everyone, but it seems that other players and/or groups have adjusted their basing to their liking. My gaming group has also done this, but for different reasons than most others.
The basing can be whatever your gaming group would like it to be. For 15mm figures, the Lasalle book recommends eight infantry figures on a base with a base width (BW) of 1-1/2" or 40mm. Keep in mind though that 1-1/2" actually equals 38.1mm. This base width (BW) is used for the infantry (8xfigs), cavalry (3xfigs), and artillery (1xgun+figs).
As long as everyone uses the same BW for their armies, it doesn't matter what that BW is. It could be 1", 1-1/8", 1-1/4", 1-1/2", 2" 3", 20mm, 30mm, 40mm, 50mm, whatever.
My gaming group for example uses bases that are 30mm-BW x 24mm-Depth, and we mount six 15mm infantry figures per base. Why? A lot of our collections have figures that are on 1-1/8" (about 28mm) bases, so we do not have to re-base everything right away. For ranges (firing and movement), we just use 30mm BW. Some of the older bases are 28mm (until re-base) and we found that the 2mm doesn't really effect the game all that much. And if a situation ever does come up that it will, we take this into account.
So, I would say go with what works for you and your gaming group. "The most important criterion is that you and your opponent use the same system for basing figures. The second most important criterion is that you like the way your figures look!" (Page 5, Lassale rules)
The other reason, and the main reason for the six infantry figures per base is that most of our miniature collections are based for 1:30 ratio gaming, so 24 figure units are the norm. Sure, we can just paint 8 more figures per unit, but when you have 100+ units - meaning 800+ more figs to paint - and a lot of the figures are no longer produced - it makes it very difficult.
Don't get me wrong, those 32 figure "Lasalle" units look great. Heck, I even think 40 figure units (10 per base) would look even better. But most of our collections are based for 1:30 ratio games, and so forming 24 figure units is easy-peasy, and 24 figure units still look good.
So what happens when we are faced with a new opponent who has based their figures for the 40mm "Recommended" BW? Easy, we had made some 10mm decorative extenders that turns a 30mm base into a 40mm base. Bingo, we are ready to play with groups that use 40mm BW, making our Napoleonic armies are more flexible.