Apologies if I am oversimplifying or just being lazy:) but this is the main reason I haven’t spent more time on it honestly. Let me know your thoughts.
The answer is not very clear cut. Learning tremolo helps out with other things, mainly accuracy and precision in arpeggios. Tremolo is also sympathetic motion on steroids and is the most intense use of the a m compound stroke I talk about in the linked video and in the Giuliani Book. For those reasons, tremolo is a great addition to practice time.
Pete brings up the valid point, however, that not many pieces make use of tremolo. And even fewer use it through the entire thing. Around the net in in books various books, you see ridiculous tremolo routines that could take hours.
Technique practice should take up a small percentage of your practice time. 25% is a good number to shoot for. Adding tremolo to your technique routine is not a bad thing, but be careful. Don’t let it take up too much time, and always evaluate. If you feel the addition of tremolo is helping you progress, keep it up. Otherwise, drop it.
Classical guitar has been a part of my life for around six years now. Before that I was a metal head. During those six years I’ve made a lot of improvement without really practicing tremolo seriously. Don’t feel like your missing out because you’re not practicing it. Let’s be clear: just because you’re learning tremolo doesn’t man you should attempt Recuerdos straight away (please don’t).