When I decided to become a freelance web copywriter, I had to set some sort of pricing structure that I knew would satisfy both me and my clients. You can see it here.
One of the elements of my pricing structure that I never expected to be controversial was my decision to charge according to the word count, rather than the time taken.
Evidently most freelancers need a brief on the project at hand, then estimate how long they think it will take, and then quote an estimated price on that basis. This might mean paying a deposit up front, or renegotiating the price later if the job turns out to take longer than expected.
To put it simply, I can't be bothered with that kind of hassle. Why should it matter to you how long something takes me, as long as you get good-quality content in time for your deadline? And if that deadline is hours away when you get in touch, why should you pay me for two days' work?
Time and Typing
Frankly, unless your project requires an excessive amount of background research, or there are legal reasons why the copy will need to be tweaked over and over until it really is word-perfect, I see time as an irrelevant distraction.
If you need 1,000 words of 'normally' researched, well-written content, I know roughly how long it will take me, and I set my price accordingly. If you need 500 words, it'll take half as long (and require half as much effort), so you pay me half as much. It's not rocket science.
Every Word Counts
In terms of search visibility, every word counts. In terms of my website copy, charged by the word count, I'm not going to split hairs over the odd 15 words or so.
If we agree a word count up-front, I'm not going to charge you any extra if I go over it - although obviously I'll aim to get as close to your requested target as possible, if your site has fixed-size boxes for its content.
If we didn't agree a word count in advance, I'll let you know as soon as possible roughly how long your content is likely to be, and quote you a price (typically rounded down to a convenient whole number).
Either way, you know how much content you're getting and how much it's costing - again, with much more clarity than if I charged by the hour.
The Short Tail of It
I suspect anyone who charges by the hour still tries to get a target word count set out for each project, and probably uses that to decide how long they think the job will take. The whole argument is somewhat moot, on that basis.
However, I put a lot of thought into my pricing structure - and I'm still confident it's the best way to work. As anyone who's used my copy will tell you, it's definitely not true that paying by the word gets you an inferior product.