My experience is that the majority of such signalling is around the time that will be needed. You look at a new project and think to yourself it's probably about 6 months work. Your manager tells you that it "has to" go live in 2 months. And then somehow you end up saying "Okay, we'll try" instead of "That seems very unlikely". Even if the previous overdue project was quite similar.

Technical people are not comfortable asserting a realistic schedule to management and management is not comfortable asserting it to shareholders.