deadlines exists because managers believe that the team will focus to accomplish the goal. the reality is that _most_ managers are lousy at estimating the amount of time a given task takes and _most_ developers are cowards to stand up to a manager and tell them this. _everyone_ sucks when it comes for planning for the unexpected. in the end, all deadlines do is cause unnecessary stress and disappointment for _everyone_ involved.
i'm no different and have been caught up in this game more times than i can count, yes, i suck too. later in life i've come to determine, that whatever deadline i have in my head, i just extended by a factor of 2.5. if i think it will take a month, i say two and half months. that is more than enough time to not only get the project done, but also deal with anything that crops up unexpectedly. my serenity is worth more to me than looking good or being a hero.
Lack of courage to stand up to the manager might be the case sometimes. But sometimes it's also just realizing that it is futile because they are not open to it hearing it.
I remember one meeting where I watched an engineer make a good faith effort to estimate time honestly and accurately, they said the number, and then the manager came back with a time period about half as long.
In that situation, the manager and engineer viewed the discussion in completely different, incompatible ways. The engineer saw it as a process of attempting to find the answer to a question about the world. The manager saw it as a negotiation. It looked like the engineer was frustrated with the manager for trying to treat facts as negotiable. And the manager was frustrated at the engineer for not being aggressive enough.
I'm not sure what the solution is. I'm sympathetic to the manager in a way because there is a natural tendency to ask for lots of time. Why wouldn't you, if you can get it?
IME, if the manager is primarily coming up with the estimates, rather than the team, you're doing it wrong. (And are doomed to an eternal cycle of blame, stress and lack of trust.)
You don’t know how this game works. Of course the devs come up with the _initial_ estimates - they have to, or else it wouldn’t be possible to blame them when they end up delivering “late”. But those initial estimates are always “negotiated down” to whatever looks best on the manager’s quarterly bonus review - they might not be brilliant at designing products or scheduling, but they’re geniuses when it comes to re-stating things so that they sound different but are actually the same until you finally get tired of arguing with them (I mean, it’s tricky to argue with somebody who decides whether you get paid or not) and agree to whatever they say and just disappoint them later.
We tend to try to do any vaguely longer term/important estimation as a team exercise, which ends up with people talking each other's estimates up, not down - you explore the problem space more effectively as a team and a lot of "but what about X" stuff comes out of the woodwork then.
If you have a manager who sets your team up for pressure and failure by artificially revising your estimates down, without cutting the scope of the work, then personally, I would find a new manager. Source: Am a manager.
i'm no different and have been caught up in this game more times than i can count, yes, i suck too. later in life i've come to determine, that whatever deadline i have in my head, i just extended by a factor of 2.5. if i think it will take a month, i say two and half months. that is more than enough time to not only get the project done, but also deal with anything that crops up unexpectedly. my serenity is worth more to me than looking good or being a hero.