Honestly, I don't really know. I struggle with blocking as well, and I don't know if it's something that goes away. Sometimes I can tap my leg with the syllables as I'm saying the difficult word and that helps, but sometimes I'll just stay stuck until I give up on the word or try to find a new one. Another tactic I've learned on this sub is to try and avoid planning your exact words before you say them. If I think about an exact phrase before I say it, I'm more likely to get stuck than if I try to improvise on the spot (if that makes sense?) I think it avoids the pressure of depending on a particular word that you may get stuck on.