Simon, if you are playing everyday, how long do the strings last? I mean how many weeks do you get out of them? I play only about a half hour a day now, but when I was playing 2 hours a day, I would have to change strings about every three weeks. That's about 40 hours out of a set. I must admit that the D string windings are pretty skanky by that time.
Some times I change them sooner, like when the guitars strings are so stretched in that they stay in tune over night. I will change them so as to avoid a string possibly breaking. It doesn't seem to matter what brand I use. Dogal Diamante, Ramirez, D'Addario, and Savarez are all brands that I use. The Dogal Diamanté trebles seem to last the longest for me. but the D strings on all of the sets I use seem to last about the same.
Now that I am only playing a half hour a day, and sometimes not at all, the strings seem to last a good long time. I still have to change them about every six to eight weeks, due to the fact that they don't sound as pleasant after 6 to 8 weeks of being on the guitar.
Besides, D'Addario is cheap. If you have to change them frequently, at least they don't break the bank. I only use the Ramirez strings, which are hella expensive on one particular guitar, as it seems to make it sound extra good. Otherwise, it's usually D'Addario.