In old newspapers, abbreviations were used to save space. Abbreviations were used to shorten many words - the most notable being given names as well as addresses.
Remember that your search criteria is just a series of letters that are matched against a search index that was created from the scan and OCR process applied to the subject newspaper page.
Your search index database is not smart enough, for example, to interpret "ave." for the word "avenue." So, if you are entering "335 14th Avenue" - if the search index includes "Ave" the search will not be successful. Therefore, you must search both "335 14th Avenue" and "335 14th Ave" to get all possible results.
Here are some examples of abbreviations that you should employ in your search criteria:
There may be many others, so you need to search for abbreviated words as well as entire words to maximize your search results. My guess is that you can increase your pertinent results by as much as 10%.