We've all read something we wished would have been shorter.
Whether you're writing a blog post, a journalistic article, sales copy or the penultimate installment of the greatest epic fantasy series ever, you have to make decisions about length.
So, what's the ideal word/page count? The answer's the same regardless of what you're writing.
No, I'm not saying blog posts and fantasy epics should have the same word counts -- and, trust me, I'm not going to post 110k words on word count here. There's a solid guide on word counts for different genres here, but listen to what C. S. Lewis says:
"To say the very thing you really mean, the whole of it, nothing more or less or other than what you really mean; that's the whole art and joy of words."
I would suggest Lewis could have said it more succinctly. Here's my edited version:
"To say what you mean, no more, no less -- that's the joy of words."
The bottom line is that every word you write should count and you should say what you need to say in as few words as practical. Whether they're reading your sales copy online or thumbing through the first couple pages of your novel, you have the reader's attention for a limited time. Don't waste it. Unless you write textbooks (i.e. required reading), readers will move on if you're feeding them fluff.
Cut every word that doesn't move your story forward.
And now, lest I ignore my own advice, I'm going to stop.