The long answer is: "Uh" is annoying and can change the meaning of your sentences. Last night, a student tried to say:
- We went to the beach by car.
- We went to the beach buy a("uh") car.
There is at least one TOEFL speaking teacher in Tokyo who recommends that students say "uh" when they speak English. This may be the worst advice in the history of language teaching.
日本語を話そう外国人に「もっとえっとというべきだよ]は良いアドバイスと思いますか？ I certainly hope not.
Please use English well.