If you’re newer to this or your budget is tight then it is absolutely possible to produce and mix a release-ready song in one studio session.
This is how I typically work with artists. In session one we review your song and make any tweaks or changes, we discuss production direction and build the core of the production. In session two we record vocals and backing vocals and finalise the mix.
If you have produced your own track and it needs mixing then we can do this remotely or in person