Creating a new admin account for every person you would like to have limited time full access to your site is not ideal. Controlled Admin Access can solve that problem. It creates a user with temporary admin access to your site. Webmasters can choose which pages in the admin area should be restricted.
Webmasters have the option to expire accounts after a certain number of days have passed. They can add and manage users from the back-end and pick/choose which pages to give access to. They can also see a list of current users and their account information conveniently. This is a free plugin.