I think only is the most misplaced word in written English! The rule is that it must be placed as close as possible to the word or phrase that it qualifies.
These examples show you how the position of the word affects the meaning of the sentence.
1. Only Sam goes to the market on Saturdays. (No one else goes to market except Sam.) 2. Sam only goes to the market on Saturdays. (Sam does nothing else except go to the market. Sam does not eat, drink or sleep.) 3. Sam goes only to the market on Saturdays. (Sam goes nowhere else except the market.) 4. Sam goes to the only market on Saturdays. (There is one market in the area and no others.) 5. Sam goes to the market only on Saturdays. or Sam goes to the market on Saturdays only. (Sam goes on Saturdays and no other days.)