depends on horse and what clip. have done 6/7 trace clips on smallish fine coated horses or 4/5 full clips on larger not so fine horses. corses and dirty coats less than clean fine coats. so i put 5+. well two winters ago i did sround 35 clips with 6 blades sharpend to start with these clips ranged from bib clips on ponies to full clips on large comp horses.
Usually 2 or 3, but there is nothing worse than the blades going blunt half way through the clip so I usually sharpen mine after the 2nd clip.
I clipped a couple of ponies last week though and the blades were definitely blunt by the end of the 2nd one - both very thick, scurfy coats! Only did a blanket on one and a full on the other so it definitely depends on the type of coat.