There was an extensive consultation on this last winter. The summary was that should means should (ie should doesn't mean "if you feel like it"). I think the revised guidance, published at the start of July, should feature on all trustee meeting agendas in the latter half of 2015.
The updated ‘Essential trustee’ breaks down the trustee’s role into 6 clear duties: ensure your charity is carrying out its purposes for the public benefit comply with your charity’s governing document and the law act in your charity’s best interests manage your charity’s resources responsibly act with reasonable care and skill ensure your charity is accountable Under each heading, the commission explains the legal requirements that trustees must meet, and the good practice they need to follow, to operate effectively and comply with their duties. From there, you can go to more detailed guidance if you need an in-depth understanding. For example, there are links to guidance on fundraising, making better decisions and reducing the risk of liability. The commission also provides a summary guide if you want the headlines at a glance.