A mastering project includes a personal intake (after your initial e-mail), a quote if there are additional wishes, a few testrenders and a final master. I deliver masters that are tuned to your goals.
It depends on what you want to achieve with the music. I can help you fix technical issues. Sometimes I suggest you go back again to fix something in the mix, but I can also take that responsability (when we agree on the price).
It also depends on where you want your music to excel, vinyl, cd, streaming, even cassette. A vinyl album requires slightly different master than a CD album. And streaming platforms have specific sound levels that are best taken care of already in the master.
Stem mastering can lead to much better results than just a final mix. But it also requires more time because of the individual tracks that need attention.