u/Time-Cardiologist-32

So I recently started a Push-Pull-Leg split system which I really like and I've seen some recommendations say to hit this 2x a week while others say once is enough if you go hard enough. My schedule doesn't really allow for me to make it to the gym 6 days a week but 3 is easy to hit everything. Should I be worried that I'm not doing everything twice if I'm hitting failure on sets?, does anyone who does this system notice a huge difference going 6 days a week?