well today i was thinking about non-ovelapping channels like 1_5_9_13 but for US or  Canada 12 (low power but OK) ;  Then it hit me!!  
 4 channel layout for US:

OFDM subcarriers use 16.25mhz / 2 = 8.125 then
2412 -2462 = 50mhz
tail e head  -16.25mhz  so there is space for two non-overlapped channels with some guardband
(channel 1 center freq) 2412 + 8.125 =  2420.125
(chan 11 center freq)   2462   - 8.125 =  2453.875           2420.125 - 2453.875 = -33.75   
 
2420.125 + 8.125 = 2428.25  (~ new channel 4 )

2445.75 + 8.128 = 2453.875
2462 - 8.125 = 2453.875

the thing is how to use this in newer N AC...