There were definitely some letters appearing in more than two words, e i l n p r s t for starters (although in some instances one placement of a letter was included in more than one word), at least in my answers!
Following your example I had the same letter in the squares numbered 1 and 2 and at the bottom of the column containing 6 and 9, making it part of 4 words.
Mind you, what you say about the letter in the square to the left of 1 makes me wonder whether I had the answers to 1 correct, and if not what else they could have been while still completing the grid...