I was assigned to design a web page, which has a lot of control buttons. Each button requires an activity indicator, to tell the user that the corresponding action is in process. There are some actions that are disabled while one action is in process. So my main question is that, currently there are too many small indicators, will it be a good idea to use a single full page overlay indicator instead?
I run into this issue often, and my personal approach begins with determining if the user is able to work with the first data items to appear on-screen. For Example, if 3 of 7 total items appear and the user can begin scrolling through data, taking next steps, or otherwise be productive in some way then I leave items to load separate. If all the data is going to load at or near the same time, or it the data offers the user nothing without the other items also being loaded, I go with a page overlay and single indicator.
Suleiman Ali Shakir has written about his perspective on loading indicators, why they can be bad, and alternatives to using them. It's a great post; you can check it out here: