Rolled on and brushes don't give the cleanest look on such smooth products.

For an investment that is static in nature, this works OK.  

While a certain % of vacant properties may become occupied by the time you mail to a static list, the object is to identify owners and heirs of the subject vacant properties and find a way to reach them. 

You have raw land,semi developed,and developed.Raw land is where trees and everything is untouched.Semi developed is usually where they might have torn down the house and cleared some trees.Developed is where it is cleared and graded,utilities and entrance is in place and they just haven't gone vertical with any structure yet.The best use of a parcel of land might not be it's current zoning use.When you want to build on the land will factor into it as well.Example a developer might have gotten zoning and approval for a particular use.Now too many of those properties have saturated the market or the demand is no longer there.Now you have to figure out in the current economy what would work there and what the ultimate rents would be to determine a price for the land.How much dirt you have to move around to get a site ready for vertical improvements is key as well.You can have 2 sets of the same size parcel.One is listed at 300,000 and acre and the other at 175,000 an acre.Looking at face value you would think 175,000 is cheaper.You learn however that with the topography of the land to clear the site ( 3 acres ) will cost 200,000 an acre.The other parcel at 300,000 will cost only 50,000 an acre as it is relatively flat already with little to no brush to take down.So 300,000 times 3 is 900k plus 150k for clearing land is 1,050,000 to get site ready.Land at 175k is 525k plus 600k in clearing costs is 1,125,000 plus the site will take longer to get ready to develop.Land prices are down in mnay areas as well because used to a developer could form an LLC and pay any price and it the project tanked they could walk away non-recourse.Now lenders want heavy down payments,recourse,and cross collateral of the developers existing trophy properties.So now developers are real picky on what price they will pay for a property.I can go much more in depth than this about land development but I don't want to write a book here.If you have a more specific question just ask.I only provided basic info here and does not include anywhere near all development costs.

Both are going to be slow and expensive relative to other options in the marketplace.Depending on your investment goals, an IRA account held by a trust company as custodian may make sense (singular, more static assets) or you may wish to evaluate a Checkbook IRA LLC or Solo 401k (multiple assets or time-sensitive/transaction-heavy assets such as rental property).There is a lot of good info here on BP on the various plan types and usage for investing in real estate.  

All the motors come from China and the brushes are cheap, so the motor looses power fast.

Also keep in mind,  in order to give you a warranty on foundation work the foundation company WILL require that you pass the hydro static water pressure test, after they complete the work.

As Steve's implies, none of these formulas are static.

I wonder if wholesalers in other industries experience the same type of static?

As for the time I've never measured it, however if I get the desired level of profits it'll be a moot point, especially since I won't be swinging hammers or paint brushes.