I think its both but ultimately if you use the right products you could still have a bad hair day if your technique is wrong. I have a product routine that works wonders for me, and one day I did it and my hair came out looking 'meh'. I then did the routine the same the next time I washed and my hair was fabulous!
I realised the reason: when blowdrying, pixiecurl method, on cold (both times) the first time I was holdling the dryer to my head for about 30 seconds then changing it, and doing that the whole time. The second time I held the drier on one spot for about 2 minutes, and then did that the whole time. That was the ONLY thing different in my routine so blowdrying on the same spot for longer gives me bouncier, tighter curls
Also length of plopping time can alter curls, type of tshirt I use (big or small, small ones make my curls tighter on my head so the curls come out bouncier again).