Pilots have a concept of Aviate, Navigate, Communicate. This is the order of priority for them.

To restate for bicycling it could be Balance, Avoid Obstacles, Signal Intent.

I don't know whether it is strictly required legally for you to signal, but I'd suggest the practical reality is that you only signal when it is safe to do so and communicating with vehicles behind you could increase your safety.

For example, I wouldn't signal stopping if I was riding up to a red light or turning left, but generally would signal turning right (in the UK context) well in advance so the car immediately behind me knows what I'm about to do.

Pilots have a concept of Aviate, Navigate, Communicate. This is the order of priority for them.

To restate for bicycling it could be Balance, Avoid Obstacles, Signal Intent.

I don't know whether it is strictly required legally for you to signal, but I'd suggest the practical reality is that you only signal when it is safe to do so and communicating with vehicles behind you could increase your safety.

For example, I wouldn't signal stopping or turning left, but generally would signal turning right (in the UK context) well in advance so the car immediately behind me knows what I'm about to do.