Let's assume three factoids: an aspiring writer has a secure day job he/she doesn't hate, and makes a decent middle-income living at; the author queries and you offer representation; you secure an advance on their manuscript equalling two years income for the author, let's say $120k.
Are there expectations that the writer will now quit that job and get to work full time doing the things people who make a living writing do (polishing the accepted work, reviewing other existing works, beginning new works, marketing)? It's a turnabout on the question about agents working hard enough for writers--is your new client working hard enough for you?
That cacophony you hear if you lean slightly left is every agent and editor in the world screaming "Don't Quit Your Day Job!"
No one expects a writer to quit a day job. Not ever.
Usually when you do, we weep.
I understand it's hard to meet deadlines with a full time job, but a steady income with health insurance is not something to give up lightly.
Publishing income is erratic at best. That $120K is NOT a usual size advance (would that it were!) and the advance could very possibly be the last money you see from the book. Most books do NOT earn out (ie do not earn royalties.)
We expect writers to do a lot of things, but that isn't one of them.