Early in my business career (as a small business owner) I read somewhere (paraphrasing): "It generally takes twice as long and costs twice as much as originall

Early in my business career (as a small business owner) I read somewhere (paraphrasing): "It generally takes twice as long and costs twice as much as originally estimated." Amen! Rarely has the rule of thumb failed me over the last 30+ yrs. Whether it's a project around the house or a client's new feature request*. It works. I wish I had $20 for every time I've seen someone else's best case scenario estimate knowing that nothing ever goes as planned. Humans and life so rarely work that way. * Clients aren't aware of the initial estimate, they get the rule of thumb version.