I've had arguments with PM's about this. After a few years of doing similar projects you can sort of squint sideways at something similar and have a gut feel (i

I've had arguments with PM's about this. After a few years of doing similar projects you can sort of squint sideways at something similar and have a gut feel (if it's completely different from anything ever done, that doesn't work of course). But every PMP (tm) certified PM I've worked with thinks if you can just break the project into granular chunks, estimate those, then sum the estimates, there's your final deadline. The fact that it never works doesn't dissuade them on the next project is the depressing part, it's all just theatre for the execs.