Depends.
1. Not all limiters can do -0.1 or -0.3 or even -0.5 without intersample overs. If you don't know for a fact that yours can, you're better off being more conservative. If your limiter doesn't do at least 4x oversampling internally, I'd suggest never going above -1.0 dB.
2. If your ultimate target is an MP3, you need to leave even more headroom, regardless of how good your limiter is. To be
certain an MP3 won't exceed 0 dB you would have to set your brickwall limit to -3.0 dB. In practice, -1.0 dB will usually be OK, though, except for ultra clean genres such as classical or folk.
3. Peak limiting is only indirectly related to perceived volume. It's entirely possible to achieve competitive loudness without exceeding a -1.0 dB maximum peak, or even less. Perceived loudness is all about average RMS, and when you lower your brickwall limit you raise RMS, so sometimes setting a lower limit will actually make your mix sound louder.
Since you asked what individuals use, I use -0.1 dB for CDs and -1.0 dB for MP3s. But I do so only because I know with certainty that my limiter is capable of assuring that even intersample peaks won't exceed my given limit.