As mentioned above, LashBase have changed their policy for patch testing. My daughter does lash extensions and I do lashblifts, both using LashBase products and we ALWAYS patch tested new clients. I still do patch test my lash lift clients (with every product I use including eye pads!) and my daughter still offers all new clients a patch test and will even drive to their house to do one even though we're home salon based! However, as it was explained that a patch test gives no guarantee that the client won't have a reaction when they actually have a full set of lashes done, I can see why LashBase have taken this stance.
My daughter was originally taught to patch test behind the ear, which we now know to be wrong, but even attaching a couple of lashes to the clients lashes won't necessarily be enough to determine if they are going to react or not, and as I know from my sister in laws experience, you can be absolutely fine for years and then suddenly develop an allergy, even using exactly the same products. In fact, it's far more likely that you'll develop an allergy after a build up of exposure, rather than the first time.
So it is a tricky one really! we have just renewed our insurance and I mentioned this, as I like to be thorough and they said as long as manufacturers guidelines were followed they are happy. Obviously I have no idea if it came down to it whether they would still stand by that and I hope we never need to find out!