Dave Barry wrote a humor column for The Miami Herald from 1983 to 2005 and also several humorous books. From one of his stories about doing a plumbing repair I picked up the phrase “the hidden bummer factor.” Unfortunately I have found it useful on quite a few occasions.
The hidden bummer factor, HBF, is an extension of Murphy's law typically presented as "Anything that can go wrong will go wrong". After it has gone wrong we discover the reason it went wrong was the hidden bummer factor.
The HBF can appear in almost any form, mechanical failure, unfavorable weather, another contractor falling behind schedule, backorder delay, illness, schedule priority conflict, etc. I’m not sure what the best formula is for including the HBF in planning a project but some time and expense must be allowed to cover it.
In my experience, the mechanical type HBF crops up most regularly when doing installation work, especially if it is out of town and and in a location far from any commercial district where corrective equipment or supplies could be purchased.
Often the HBF initiates the purchase of new or the replacement of old equipment. This year I replaced an extension ladder and a hammer drill and added a portable generator. This adds value to the capital assests ledger but certainly doesn’t help the bottom line.
Obcessive contingency planning will to some degree corral the range of the HBF and seems to be the best strategy. Eternal vigilance is the price of liberty and also profitability.