It's like someone that's never painted in their life giving estimates on how long it'll take to paint the interior of a new house based on the total width of al

It's like someone that's never painted in their life giving estimates on how long it'll take to paint the interior of a new house based on the total width of all brushes that'll be used and the total area to be brushed. Even if it's small and you'll have a lot of brushes, there could be lots of detail work because of windows/doors/etc. Who would have a better idea? Probably someone who knows how to paint.