50 was fine for me until I decided to get Amethyst up to date on an old phone. For version 0.94 I had no problems.
Amethyst 0.94 and 1.0+ handle relays in fundamentally different ways. In the old version you needed more relays to find posts. Now it uses outbox and other people's relay lists are used to find their notes. That way even if you and I don't have a common relay, we still find each other's notes. A large list of relays is no longer needed, and possibly detrimental.