[email protected]I strongly urge you to get another job lined up first that is less demanding as someone has suggested above.
It's easier to get a job when you have a job and if it ends up being a situation where you are long-term unemployed you'll be flagged as a high-risk candidate by the admissions committee and that will decrease your chances of being accepted.
And so in that case quitting your job to improve your test score might or might not work out and is not going to result in an admit.
Change the job but just don't expose yourself to an unlimited period of unemployment...this is an application killer unfortunately.
Find a job that's more related to what you want to do and one that requires less physical effort and allows you time to do the GMAT.
I will also offer my most successful clients - as a former GMAT verbal tutor of 18 years - woke up ONE hour earlier and spent an hour studying everyday. Giving their best energy to this before the day was over.
https://mbaprepcoach.com