ArenaNet announced an interesting news and it will affect players who used transfer server to get more materials. You can only transfer worlds once every 7 days starting november 1:
Due to community concerns about the effect of free transfers on world versus world, starting on November 1 we are going to change how often players are allowed to transfer worlds. After the update, players will be able to transfer worlds once every 7 days instead of once every 24 hours. We are also actively working on getting the guesting functionality in place. Thank you for your understanding.
Source: Martin Kerstein Head of Global Community from ArenaNET