sov for troop production

Ideally, for exceptionally fast troop production, you will need 6 of the basic that is required by the type of troop cost reduction building (for example for spears it is clay and iron) so a 6 clay is required. 

Using that, with only prestiging the basic that only has 4 plots, you can get 18x lvl 3 and 2 lvl 4 (roughly).

If you decide to prestige everything, you can run close to 17 lvl 3 and 3 lvl 3, though you are still negative on 3 of them, though it is manageable. 

See the pic below on one of my setups. If you do run out of basics (and it has happened), it normally drops one or two off, so it doesnt take long to get back there again. 

As for switching, it does not take that long to switch from lvl 3 to a different lvl 3. 

It all depends on the setup you are running.  This is not a viable set up for a 7 food town as it is simply not able to be sustained easily. You could do it, but really who would want to, it is bad enough with the small levels of negatives that I have in this town if you decided to really run high negatives, then you are chaining yourself to your account. With these level, I can leave them for a while and not bother checking them. 

For players that run 200% or so, that is a very easily doable and sustainable amount to achieve. At a minimum, you really only need 6000 basics to do and if you prestige build the town, you can get there very quickly and start producing troops. 

Cheers,

He-Man