There are so many variables between person to person, horse to horse and day to day that it is almost impossible to say how long a blade should last compared to another. You can only compare them fairly if you keep all variable conditions the same, this is not what happens in everyday clipping.
Sharpen them when they start to go blunt. You know they are getting blunt if you are having to increase the tension more and more to get them to cut.
My clipping is fairly easy. I do my own ridden two regularly (full clips, one with legs and head - fine warmblood coats). I do a few others too, mainly fine coated. One heavy coated, ?cushingoid horse.
I have three sets of blades now I think, and rotate them so a set are off being sharpened whilst I have two with me, then send a set off when those come back. In summer I will have 3 sharp sets ready to go for the winter.
You will also find a difference dependent on how the blades are sharpened. Some firms use a special disc grinder with an abrasive paste, whereas the true professionals will use a "lapping" machine which will only take off the amount of metal required to give a good edge and is set and calibrated every day to ensure a consistent result. Also some firms do not "hollow grind" the blades as they should be done. Especially those who try and sharpen pet blades and horse blades on the same machine. It pays to ask before sending blades. Also, the number of times you will need your blades sharpened, will depend on the state of your horses coat. A greasy or dusty coat will take the edge of a set of blades very quickly. It pays to shampoo and groom before clipping. Another thing which can have a highly detrimental effect on blade life, is oil. Many people still seem to think that WD40 is an acceptable lubricant.It is not! Also some companies have brought out "alleged" dry PTFE lubricants, which it is claimed are suitable. I have yet to find one which is. Look at the oil you get when you buy the machine and buy a similar type when it runs out, or buy an oil produced by people who make, or sell clippers. It is not in their interests to sell rubbish. Most important, get the tension right and combine all these factors, then clipping will be a breeze.
Agree with all of the above. My last horse had quite a fine coat, being half TB, and I could get several hunter clips out of one set on him, even though he was 17hh. Horse I have now is smaller but quite a cobby type with a very thick coat and I can only get maybe 3 clips if I'm lucky from a set of blades now. I made the mistake of not bathing him before this year's clip (it was too cold and it would have taken, quite literally, days for him to dry as he was so hairy) which didn't help the life of my blades as the coat was oily.
Bye bye everybody!!!! Just to say cheerio, after posting for some time to try and help people with clipper related queries, I have just got a job back in the clipper trade...yayyyyyyy! Sadly forum admin have decided to take offence because I dared to mention where I have gone to work and threatened me with suspension of my account, even though my new employers actually advertise with Horse and Hound....Hey ho. Sadly I don't like bullies, or people who let power get to their heads. All I have ever done on H and H is attempt to give un biased and fair advice for FREE. Obviously that is no longer allowed so "Trot on H and H". Happy clipping all you folks out there in clipper land and remember my last salutory bit of advice. If buying a clipper or blades, remember you get what you pay for and you get the service you pay for. We can all buy machines and blades for £150 of E Bay, but they are more than likely going to be made of recycled Chinese Aircraft Carriers or not pass EU safety regs. Or we can pay a bit more and buy from a recognized brand, with backup, spare parts and safety in the knowledge that the manufacturer will still be there in years to come. We take our choice. Ride safe, clip well and love your horse.......