Modern Arnis is typically an art of the single stick.
Many training groups only use double sticks to do a few sinawali drills (coordinated "weaving" patterns).
Here's a clip of my instructor teaching a drill where we have one person with two sticks attacking someone with one from a few years ago (yes, that's me driving). In this drill, it's much, much harder to be the attacker, or driver (two sticks) versus the defender (one stick), as you have to think ahead.
Another advantage is that double stick work translates very smoothly into empty hand techniques.Some of our most basic two-stick techniques, like the "Combative Responses" borrowed from Kombatan, directly translate to useful empty handed techniques for self defense.There is a right way and wrong way to hold a kali stick when stick sparring. When holding your rattan stick, always allow enough room (approximately one fist length) on the bottom portion of your weapon.First, when you hold your kali stick in this fashion, it actually converts one stick into two weapons useful weapons.If you can do it with sticks, you can do it with any of the other double handed weapon sets.
This makes the Filipino Martial Arts and our training methodology very flexible in terms of application. a single stick is an interesting way to solve problems of inserting and chaining together techniques and patterns. one stick drill progression starts pretty early in our curriculum.
Grasping your kali stick too tightly when fighting can be problematic because it will tire your hands and cause unnecessary cramping.
Your stick strikes will also be telegraphed and the speed and power of your strikes will be significantly reduced.
It's also what we use to prep our students to perform tapi-tapi - the mental skills, as well as physical skills.
Finally, double stick training is just plain fun, especially when you explore different sinawali patterns that are out there (or make up your own).
Most importantly, the rattan stick is also safer than wood because it does not splinter on impact. This is especially important when performing full contact stick combat techniques with your training partner.