With millions of members all over the globe, reading one day's mails will take a month or two.
I agree. I think the idea of local lists is that you can discuss local issues without being buried under the load of unwanted mails. However, at times and with care cross-posting can be done. For example if India goes for FOSS policy, where would one post it? It should be posted at as many LUGs possible so all members are aware and participate. Similarly, if one has a problem and need immediate solution should she post only to one list assuming someone on this list only will have the solution?
Cross posting is tricky and should be done with care realising what you want to achieve.
Swapni