A block is basically the clamping shut of vocal chords *because we’re are trying so hard to not stutter*. I suspect the cracking voice comes from this too. When I’m even subconsciously worrying about speaking (extra swallowing) or drinking lots of extra water, I end up more thirsty. As long as you are still trying very hard to not stutter, no amount of techniques or tricks will result in fewer blocks. Stuttering is very counterintuitive - the harder you try to fix it, the worse it tends to get.