There is no context for this included in your question.
Are you using this as a publication for academia? Or a poster for your local band? A blog? An advertisement? Every different use can have different criteria for an answer. Designers will often change the tracking between letters and/or adjust the space between words depending on usage, content, surrounding text and graphics, different visual intents, etc.
Also the chosen font can have a great impact on choices about spacing. A serif font can require more spacing while a sans font can be closer spaced (or vice versa). Is this a headline sitting by itself or is this capitalized text surrounded by other text and graphics?
I suggest that rather than having a “rule” about adding space between all caps one should focus more on specific design layouts and what intent you are trying to convey. Is it simply for readability or do you want to emphasise something? In certain circumstances yes, space out those caps a bit; in others, tighten them up a bit.
These choices are all very context-oriented decisions and to have a “rule” about whether to and how much to space all caps is only a limitation. Best to make a decision about this with the overall layout in mind and a visual check of spacing, balance, and over all flow being the factors in your spacing decision.
Personally, I find that when using all caps I prefer the spacing between words to be more important than the spacing between the individual letters. Otherwise a sentence tends to look like one long word. Again, this is very specific to the application.