During my mock cycle, my lining was perfect when I increased to 4 Vivelle patches. I had no issues with them and my insurance covered them (they cover nothing related to infertility, but I nobody specified what they were for!), so I thought all would be well.
For my real cycle, however, the 4 patches was not enough, despite the fact that my blood E2 levels were quite high. I ended up being on vaginal estrace in addition to the patches, which worked beautifully. For whatever reason, some people just need a lot of estrogen. In order to have a good lining, my blood levels needed to be almost 2000, whereas some people are fine with E2 levels closer to 300.