I guess you would need some of the popular accounting firms (cpa's) that do coop and condo audits to review the financials that they prepare and count up their annual reports to find out. Maybe that's a question for the Cooperator to ask when they mail out next year's COOP Expo invites.
At this time, the estimation is not required by any laws. It is also not free. The board would need to hire an engineering firm to examine all the properties from roof to basement, curb to curb and estimate what repairs are needed short term and estimate the useful life of major items, such as boilers and other HVAC equipment, plumbing, electrical, roof, retaining walls, etc. and project the replacement and repair costs down the road. You would need to do this probably every 5 years or so, to keep up with completed projects, aging and deterioration.
A reserve fund is your money, in excess of the current operating expenses. Few people want to contribute extra for the rainy day. It's one thing to have to pay via assessment for window replacement that would benefit you short term, it's another to sock the money away for that new boiler needed in 15 years, probably after you've moved out.