This is actually a very important skill. Use it to your advantage! When you know which word you're going to block on, there's enough time to apply techniques that can get you through the block. Word stretching, mouth shaping the vowel, light contact on consonant, inaudible hum right before the word, word-chaining, heck even substitution or a filler word right before. There's a variety of techniques you can apply to work around the faulty motor program brain has generated for your speech. The more you practice, the easier it will come when you need it.