One size does not fit all
There was a time when races would design a single flyer and use it for everything: direct mail, newsletter insert, magazine ad, poster, and sometimes even a web site.
That was usually done to save money, but it was not a good strategy.
A different piece should have been created for each venue. Using the same flyer for everything - even when it was clearly inappropriate - made a lot of races look cheap, lazy, and not very viable.
It made marketing of the race less effective.
As events drift into the digital age, this issue is resurfacing. Races that want to communicate to runners through mobile devices should create mobile apps to do that, and not rely on their web sites to convey information.
A smart phone, for example, has a much smaller screen than a desktop or laptop computer. It's more difficult for users to wade through a web site to find and read information they need. It would make a lot more sense to design something that would meet the needs and desires of runners when they are "on the go."
What information do runners want to access from a mobile device? What can wait until they are in front of a computer? Once you've answered those questions, you can design the appropriate content and format for each.