is the R rate still important when cases are lower?

[everybodysang]

Looking at the Zoe app, the R rate is quite high at the moment (1.1 UK wide, 1.5 in the South East, though only 0.8 in the East of England, where I am).
I seem to remember reading that the R rate is not as useful a tool when cases are low. I understand the principle - that if it's over 1, the rate of infections is growing - but I can't find reference to it being less useful if cases are low. Am I remembering incorrectly?

www.gov.uk/guidance/the-r-value-and-growth-rate This explains it better than I could

Calling PrincessCarrie and/or Nannyandjohn. This is your thread.

ah - yes, that does explain it well. That did come up when I Googled but just saw the figures and not the explanation below.

Well, if there's one positive to all this, I do have a better understanding of epidemiology than I ever expected to have in a lifetime.