Framing long walls in sections and keeping 16" OC Layout
I think it may help to know why 16" OC is so important and the main reason is that drywall and other sheathing comes in 4x8 sheets.  For you to properly hang drywall, you must have a stud where ever two sheets will join up.  So, as long as you have at least 3/4" of stud on either side of every 16" space, you'll be ok.

Say you make 16' wall sections... The first stud after the edge should be centered 16" from the edge of the wall - not the center of the edge stud.  This means that where the two wall sections join, the space between the two edge studs will fall directly on a 16" boundary and that's fine for joining sheathing or drywall.  Note that you should probably plan to have the sheathing joints not line up with the wall joints, but that can be handled pretty easily.

||           ||         ||||         ||          || 
||           ||         ||||         ||          || 
||           ||         ||||         ||          || 
-------------------------- -------------------------- 
    14.5"        13.75"       13.75"      14.5" 
    (Gap)




Added better diagram - you can see that if you follow this pattern, the 16" OC will continue from wall to wall.  The only issue is that where the walls join, you will have a joint between two studs that falls exactly on the 16" mark, but this is fine for drywall and sheathing.  As the other answer mentions, these doubled-up studs might cause issues for insulation batts or other items that assume a 14.5" gap, but if you want doubled studs to make "complete" wall sections, that's what you have to do.