Grammatical to use articles in this way?

"I have a pencil, a pen, an eraser and a ruler in my pencil case."

It's normal and grammatical to distribute articles to singular countable nouns. But I am always puzzled by the following:

"I have a pencil, pen, eraser and ruler in my pencil case."

Is it grammatical to just use ONE article (and omit the rest) in front of a list of singular countable nouns to represent these nouns? Some people say YES and some people say NO. But I get more confused after I spotted similar examples even in dictionaries/newspapers/lifestyle magazines.

Hope some grammar experts can give me guidance.