How can I make vendor timelines accurate and fast?

Why are vendor timelines rarely accurate?

As a client in Pharma, I used to wonder about this all the time. Now being on the vendor side, I completely understand why. It's because, until we get to know you better, we are simply giving our best guess.

We're guessing on:
-How well your strategy is solidified for a project before we start and how many times it may need to change (will you need 2 rounds of brainstorming before we get on a good track, or do you have an outline all ready to go?)
-How many reviews you'll need (do you others popping in to give feedback that varies? Do you need to look at something to react and then perhaps change course?)
-What your style preference is and how best to meet it (does your audience prefer a specific style to visuals?)
-How well you meet timelines (are you impossibly busy, so it will take you a lot longer than what we've outlined? Do you have limited time and your first look is not always as thorough as you'd like it to be?)
-What your review process is like (does your MLR/PRC have a lot of churn and change directions between reviews? Or are they straightforward and clear?)
-How well we can contact your reviewers, especially HCPs (do they need 3 weeks or 3 months in advance to get time on their schedule?)
-Will there be extra steps involved that we don't anticipate?
-Do you give good examples to work off of that allow us to meet your needs on the first try? Or will we need to supply samples of work to get clear on the direction?

Note: Guesses become more accurate once we know more about you and your needs. ;)

The moral of the story is to take timelines with a grain of salt, unless you absolutely need to meet those timelines for success (then communicate that up front, and hold to the timelines given). Be flexible, communicate as much as you can upfront, and leave some wiggle room and know that best guesses can be difficult. But most of all, be respectful of your vendors and know that we want to help you be successful!