What is the function of 一次 in "去一次"? I came across these translated examples:

[Talking about a place]:

明年夏天我打算去一次。
Mínɡnián xiàtiān wǒ dǎsuàn qù yí cì。
I plan to go there next summer.




三年以前我去过上海，去年我又去了一次，明年我想再去一次。
Sān nián yǐqián wǒ qùguò shànghǎi, qùnián wǒ yòu qùle yīcì, míngnián wǒ xiǎng zài qù yīcì.
I went to Shanghai three years ago, I went there again last year, and I want to go again next year.



In English (or Spanish), typically we would not say &quot;you go one time to a place&quot;, one time is already implied in the verb to go and it feels weird to state it unless you want to emphasize for some reason &quot;you are going just one time&quot;. Why 一次 is specified in these examples? Previously, I had understood the use of 一次 in the second example was required for 又 and 再, however the first example does not have any special structure.
Grammatically, 次 is a verbal classifier (a classifier proper), which expresses how many times the action indicated by the verb occurs. The origin of your confusion comes because classifiers are not used in English but they are natural in Chinese.
Classifiers (verbal or nominal) must come with a numeral phrase. In this sense, the numeral 一 (one) might be interpreted here having more a grammatical function than a semantic function (i.e., it doesn't carry enough meaning to be translated in the target language). Indeed, it is possible to omit the entire numeral phrase 一次 and just say 明年夏天我打算去, provided the place is clear from the context.
As an example, the sentence 我昨天买了一本书 presents a slight ambiguity, right? It could be &quot;Yesterday I bought a book&quot; (&quot;one&quot; has grammatical function, translated as indefinite article) or &quot;Yesterday I bought one book&quot; (&quot;one&quot; has semantic function, translated as &quot;one&quot;). Though without further context, you should favor the former, because of what I said above.
Finally, whereas the number &quot;one&quot; may or may not be semantically relevant, any other numeral is likely to be so.
As always, check the context:

老朱呢？我来叫他一声 = Where's Lao Zhu at? Let me call him (&quot;one&quot; is grammatical)
我叫了他两声，他还不听 = I called him twice, he still doesn't listen (&quot;two&quot; is semantic)
那本书我不太记得，我只看了一遍 = I don't quite remember that book, I only read it once (&quot;one&quot; is semantic)
请你来帮我一下忙 = please give me a hand (&quot;one&quot; is grammatical)
我被他骂了一堆 = He scolded me badly (literally, a pile) (verbal measure word (!), &quot;one&quot; is grammatical)