So I work 5 15 hour work days, food is a tiring process with such long shifts and IAM tired of eating shitty.
Think this will be good enough to supplement into staying full?
Planning on healthier snacks to go along, fruits, salads, simple stuff. Also in retrospect this is fairly cheap.
Depends - What type of job / activity level will vary on how much you’ll probably need to stay full.
Short answer: Yes
I would say first six hours low activity and the other half 50/50 up n down between highly active to light work/physical
Depending on your snacks, 4 servings evenly spaced apart - (1,600 to 2000 calories depending on what liquid you make them with) BUT of course you can always work with it and see what works with you, experiment with it. 
I work 12 hour shifts. More like 14 after mandatory break and the commute. This stuff is a miracle product when it comes to healthiness and convenience. I’m also a powerlifter and consume nearly 4000 calories per day. I usually slam a decent breakfast at 6 before heading to work. Then around 10 I have 2 scoops of Huel. At 12 I have 2 more. At 2, I go get a nice meal, like Chipotle or Pollo Tropical. Around 6, I have 2 more scoops of huel. When I get home around 8, I have 2 more. Keeps me satisfied all day, better than snacking on garbage, and significantly easier to meal prep.