Does poor technique cause this? or could it be that the wax isn't warm enough? I get really annoyed with myself when I run my hand over my clients leg and can feel some stubble.....

Its probably is nothing to do with you breaking hairs.Its more likely that the hairs were too short to be waxed in the first place,i.e different stage of hair growth than the ones you managed to wax.

Also if someone wears trousers a lot or tights then this can cause the hairs to break off, again making them too short to wax,leaving the stubble you can feel.

Try pressing your wax strip down really firmly to try to grip onto the shorted hairs.HTH

hairs can be snapped off during waxing due to wrong technique. if you pull the strip off at the wrong angle this can cause hairs to break, of course some people's hair are more prone to breaking off than others if the hair is dry or brittle.

Broken hairs is common if you have poor technique. Make sure you are removing the wax at the proper angle. Some areas of the body are prone to broken hairs, such as the groin and the back of calf muscles and inner thigh... not because of waxing, but because they are areas that tend to rub against our clothing a lot. I find that if you apply the wax in the opposite direction and then apply your strip as usual and pull in the usual direction, this gets those stubborn little hairs.

I have come across people who almost have a second very short growth all over often strong and blonde.I always have a good run up and down with my hands before i wax then you can feel if there are any short stubbly ones also have a good look and then before you even start you can advise that their legs will not be perfectly smooth because some are too short this is also a time to catch any ingrowing ones with the tweezers to bring them to the surface so you can wax them to.