I think it is very individual - some times they might go to try to say something \*to practice\* how do I know? I did that very much what you write; I walked to a store/or restaurant I do not remember; and didn't actually need anything special but decided to practice my stuttering; and one there (working in the store) helped me - numerous times; (by completing the sentences, after she asked me and I **did not have heart to say I was practicing so I said Yes since - it** would be helpful if I was genuinely trying - and it was difficult, **although everyone is different)**; (which was very very kind of them) (and it is very kind of you to to care this much **\*\*and even write a question like this\*\* it's just wholesome** :)! ​ I think; asking the person (in some fashion, if possible) do you want me to help you complete the sentences/ or similar; maybe could be something but I do not know frankly; ​ have it good! Good luck as well! :)