Why does 土曜日に予定があります sound off?

Question

From this answer,

While totally acceptable in everyday conversation, the following polite versions still don’t quite sound natural to me as standalone sentences.

土曜日に予定があります。

土曜日に予定がありません。

That (今週末、予定はありますか) sounds natural. You could also say 今週末は（何か）予定がありますか. It is the に that is making the sentences above somewhat unnatural.

It figures looking at the search results:

• sentencesearch.neocities.org
• jisho.org
• weblio.jp | 予定がある | 予定があります .

は is preferred over に, or sometimes no particle at all. However, に is used quite often.

Assuming context is not important, then my guess is that, as あります is あり + ます, あり is more along the lines of to exist rather to happen. Similarly, we say あり得る possible to exist and 起こり得る possible to happen. Under this reasoning, 土曜日に予定があり is bad but 土曜日に予定があって fine.

Answer 1

I think the reason they sound a bit off as standalone sentences compared to, say, 月曜日に試験があります is as follows. に as the time marker expects an event to be bound to a particular point of time, but 予定 is not concrete enough as an event. You have that plan now. What you have on Saturday is whatever you plan to do, not the plan itself. The listener can, and will, still make sense out of it by understanding 予定 as meaning すること as I said in the linked question, but that doesn’t necessarily make the sentence completely natural.

That said, there are times when に is the best, or least bad, choice in a subordinate clause. This happens because a time expression like 土曜日 being used as a standalone adverb with no particle seems detached in a subordinate clause, and は could add an unwanted sense of contrast.

土曜日に予定があるか彼に聞いてみよう。

When an added sense of contrast is not a problem, は is preferred.

土曜日は予定があるので行けません。

Whether an expression sounds natural or not is not a black-and-white matter. It is a function of multiple factors.