Unless you are a builder who can do it at cost, it will take a while to see a return in most markets. 

Bonus is if you can move to larger parcels that may have timber value.trying to find lots for builders is pretty much a non starter builders find their own lots.. and are not going to over pay.this is why the guys that do this primariliy are working the deserts of the south west.. high deserts of CA rural Texas NM  AZ  so on and so forth..

Builder creating speculation and artificial inflation.2.

Builders sell 1 Acer lots for 6 figures and raw land is usually in the four-figure range. 

From what I've seen it's rare that the original builder would over-design a system for a home unless the original homeowner planed to expand in the future.  

The builder is what's known as a small builder, unlike KB Homes and other more prominent developers.  

Ok seasoned spec builders,What is your most cost effective/profitable home plan?

We had to wait a day to see a property we were looking to flip- within that time someone put an offer on it :( it’s an original home built by a well known builder.

I was a carpenter for several years and enjoy getting my hands dirty - the plan is to be the owner/builder, sub out a fair amount of the construction, but add value by doing a fair amount of the planning and some of the building myself.

I'm admittedly not a professional builder but eager to learn.