Interesting, indeed. I've always thought "I sometimes used to..." is an ugly construction. But I recently gave a twist to my thinking and began to wonder if "sometimes used to ..." was acceptable. Ever since I've been rollercoasting between the suspicion of and support for the validity of the 'twisted' construction. So, as usual, I decided to resort to this forum and posted the question. Now, after reading all the comments above, for which I am grateful, I feel as if the rollercoaster were on a wilder track.