Even though yesterday is not an adverb, we say:
I played golf yesterday.
only because the preposition, on, is dropped before yesterday. In that on yesterday becomes a prepositional phrase that modifies played:
I played golf (on) yesterday.
That preposition dropping is a rule. What about Japanese sentences like:
Grammatically, is there really a particle after 昨日 such as:
昨日 (では) ゴルフやった。
昨日 (に) ゴルフやった。
In speaking, you pause instead of saying the particle, but in official writing, are those possible particles after 昨日 written (instead of a comma)?
Of course, this is not limited to just 昨日 such as:
In English legal contracts, every last preposition and comma are triple checked because they can make such a huge difference in any sort of dispute.
Now, Japanese commas seem to be void of specificity and thus open to "interpretation" by the counterparties / judge / arbiter, right? With big $ on the line, the counterparties must specify exactly what they are agreeing to, and you can't do that with commas???