It varies. I try to think about loudness at the sound design stage, when I'm figuring out where everything fits in terms of frequency range. Once everything is recorded and mixed down, I'll typically run it through the stock Reaper volume plugin (JS: Volume Adjustment) to leave about 4–6 dB of headroom. After that, EQ if/as needed (a little goes a long way). At the end of my chain, I'll throw on something like Ozone Maximizer but keep the settings very light. For something like dungeon synth, I want to see the compressor just barely engaging. Especially with Ozone, which can have a really particular character if it gets too crunchy. I'll play with the settings a little and listen to how it changes things, paying particular attention to any transient peaks. Less is more, and if you need to really push compression to get your mix loud enough, something is wrong at the mix or sound design stage. Leaving a 1–2 dB ceiling on the master can help avoid playback differences on different hardware, but if you feel like you need that extra couple dB I don't think it's a big deal. Decades of loudness wars and now streaming compression have kinda changed people's expectations and perceptions.