I was taught to do seated / lying on couch combo and I understand that the VTCT course at the local college uses the same method.
I’ve found the transition from seat to couch very un-disruptive to the relaxation experience and the clients have welcomed the lie down. In fact, many times, snoring ensues within moments of the client’s head hitting the couch, LOL. I’ve found a chair / Lafuma recliner combo works well too.
I, personally, find it difficult to fully relax unless I’m supine, so I’ve always enjoyed and indeed looked forward to this part of the routine when I’ve had a treatment myself. My sister has had both a seated and a lying down IHM and says she prefers my method.
I’ve seen a method in an IHM book by Francesca Gould where a towel is rolled up to form a bolster to support the client’s neck and head for the facial massage, this is totally impractical for me as I’m just over 5ft tall and I work barefooted or in flatties, the client’s head would rest just beneath my chin, LOL.
However, its down to choice whether you do it wearing a Sari, cross-legged behind your client on a Goan beach or you use one of those massage chair contraptions - We must remember that we should consider our own safety and comfort as much as the client’s and I know that, the way I work, I’m not putting any undue stresses or strains on my own muscular/skeletal system.