orchid - yes, you do need to use some progesterone even if you only used Oestrogel 3 times a week. To be honest, you may as well use Oestrogel properly every day and get the full benefit instead of just randomly - using it every other day would give fluctuations that might not give any real relief from meno symptoms. If you are trying to help vaginal atrophy, dryness and bladder problems then you could try local oestrogen like Vagifem which only absorbs locally so doesn't require any progesterone. However if you want to reduce flushes and other meno symptoms then it's better to use a proper dose of HRT.
Liz - I've always used Oestrogel on my inner thighs after my shower as I find this the easiest place to apply and a larger area fro application. I like to use moisturiser on my arms which you can't do when using Oestrogel. We are all different so it doesn't matter whether it's the arms or thighs really - I just worry that, if I apply it to arms, some Oestrogel might get absorbed directly to my breasts. DG x