If you are bedroom mixing your own record single (like what many people do these days). It should take you as long as you don’t exceed your initial timeframe. The essential part of the game is to meet your own preferred deadlines. But ideally, if you are not a noob. You ought to mix a track from start to finish within a day i.e., in 8 hours max. At the same time, you don’t want to rush it, you also don’t want to take too long. The same mindset applies to mastering music too: study long, study wrong.
However, a track should only take too long when you are doing some creative sound engineering wizardry with lots and lots of automation and effects. That’s kinda acceptable. Although for audio mastering there is no excuse whatsoever for the process to take more than an hour. For instance, what will you be doing with a parametric equalizer for the process to continue going on and on? Nonetheless, sometimes there’s no doubt the best way to get good at mixing and mastering is to just keep doing it. Even if it takes all night.
Bedroom mixing other people’s music
If you have to do some bedroom mixing for someone’s project. You quite frankly have the responsibility of getting the job done professionally and on time. Yes, this may sometimes involve inconvenient intense scheduling but it’s all part of the game to ultimately present your best work and build trust with customers.
You should also avoid nagging clients who continue asking for more revisions. Remember sound engineering is a business. The more songs you mix or master the more money you should make if you are doing a proper job. But if you are destroying people’s transients by punishing brickwall limiters. You may want to consider doing the right thing. In this case, doing the right thing means leaving the game for a while and getting back right in when you get better.