I don't think Amanda and Jane were super tight in S7, but I haven't seen much of it since first airing. What I remember is Amanda still treating her the same way and Jane being more charitable and graceful about it because she worked for Amanda at that point. Also, in fairness, Amanda had lost a lot of actual friends or what Amanda would consider friends. Beggars couldn't be choosers at that point.
I do think the cast was largely friends in the first several years. It wasn't until the latter half of Season 4 that they all began to really drift for me. Any excuse to bring some of them back together, particularly in Season 5, was exciting, like Alison's all too brief return to the corporate world from her Jake bubble.