It depends. If my online Master is giving me a workout, he likes to see as many toys as possible used. I often have a big clean up .... sometimes up to 6 toys.
I feel like more than one is a lot more work than I'm interested in. Even one is work because I have to clean it up well, whereas hands are easily washable.
I usually use two or three, sometimes more, during masturbation as well as PIV sex I will usually have a plug in my butt and I will use both a vibe and a dil. Depends on how much time I (we) have to play.....
Usually use more than one. Sometimes multiple at the same time and sometimes just change halfway through.
My toys of choice are vib, dildo and butt plug. And occasionly use nipple clamps, gags (or just a dildo in my mouth)and even though it isnt a 'toy' i also use lingerie and sexy heels to get myself worked up as foreplay
It depends on the toy. If it's a rabbit, that's all I need. If it's one of my favorite dildos, then I'll add a clitoral stimulator or a vibrating anal toy.
I use many toys on any given night. I like to switch things up. I usually warm up with nipple toys and a smaller dildo or a weak vibrator. I will finish off with a bigger dildo, sometimes with a stronger vibrator (or stronger setting) to go along with it.