how much gold does cto have?, page-10

Citigold claims an 85% confidence limit on their Probable Ore Reserves in their report. The industry standard for a Proved Ore Reserve is usually 95% confidence, so the difference is 10%. In auditing, a "material difference" is usually 10% or more, so the difference between Citigold's Probable and the industry standard for Proven is bordering on immaterial (but is still less confident).
I do accept that the main difference between Proven and Probable is that the geological data spacing is closer in Proven than Probable.
Many mines with irregular grades have very small Proved Reserves - the Ardlethan tin mine in NSW ran for 40 years with only ever having 12 months in Reserves, and Central Norseman gold mine (WA) ooperated for about 60 years with usually less than two years Reserves.
The critical trick is to keep replacing what you mine out each year, which can only be done by drilling and development.