Infills
Infills should be every 2-4 weeks. You should arrive to your lash appointment with 30-60% of your extensions left. The majority of my regular clients have infills every 3 weeks. During an infill we remove the extensions that have grown out and twisted, and replace those extensions that have naturally shed with your natural lashes. Humans shed approximately 2-5 natural eyelashes per upper lid, per eye, per day (lets average this at 3 per day), and your therapist will apply approximately 100 extensions to the suitable natural lashes of each eye.
Retention
You should arrive to your lash appointment with 30-50% of your extensions left. If you are not, then there will be a reason. If the issue hasn't happened to the entire client base then we will need to look at your aftercare/change of medication/hormones/illnesses/ pregnancy/skin type/makeup.
3 week infills is totally fine if your retention is good, however if it is poor you will need to come back sooner or you will be liable to pay for a full set or find yourself with a less full lash line than you previously have experienced.
Please let me know in advance if you have lost more than 50% of your lashes so that I can try and adjust appointments so we can get you back to a full set. Please be prepared to pay more for your infill if this happens.