I'm a firm believer in taking things easy and doing things as you like it
That said, you can adjust how much farming session you want given on play time on weekly or monthly basis. Personally, I take longer, probably around twice farming session per two week or even less. You can make sure your farming session is as smooth, enjoyful experience that will leave you out for more motivation instead of feeling tilted, my tips is as follows:
• Take farming responsibly, don't underestimate the difficulty of the maps that are farmable. saying things like "why tf I shitmiss?? I supposed to FC this map already??" is surefire way to get yourself tilted. So play farm maps like you would on any other maps for improvement.
• Can't FC for some reason? Let's find another farmable maps! You shouldn't be too focused on really specific maps. You want to farm, not to improve your skills at the moment
• High Acc (98-99%) and one or two misses are indication that you're ready to FC a certain map. With reasonable persistance and good performance for this session, I'm sure you will FC that map. iF not, then there's always tommorow
• Optional, you can let go of result-driven approach when it comes to ranking up. Having no expectations is better than feeling disappointed in the game for not gaining much pp than you've hoped for