I would like to make two small suggestions. When you are using "days" it would be helpful if it specified whether they are business days or calendar days. For example, when you are using days in the duration field of a gant chart they are business days. When you are using them to set a reminder they are calendar days. It can just get confusing and I have to test it both ways to make sure I have it correctly.
The second thing is permissions to sheets within a workspace. I know there is probably a good reason why sharing is based on the entire workspace but it would be really helpful to be able to set permissions on each individual sheet within a workspace. I have workspaces for projects with customers and I need to have two separate workspaces for each project. One for internal documents and one for customer viewable ones. It's cumbersome.