Learn Hardcore Japanese: kanozyo ha atarasii syokuba ni nareruno ni zikan ga kakaru. - It takes time for her to get used to her new workplace.

Here, のに is not the “even though/although” conjunction. It’s の (nominalizer) + に meaning “for (doing)” in the fixed pattern V-plain + のに + N(時間/お金/手間) + がかかる = “it takes N to do V.” Structure: [新しい職場に慣れる] のに [時間がかかる] → “It takes time to get used to a new workplace.” The “although” のに links two clauses (e.g., 雨なのに出かける). In this sentence, の nominalizes the verb phrase, and that noun-like chunk is then marked by に.

Why are there two に in the sentence?

They do different jobs:

The first に (after 職場) marks the target of the verb 慣れる (“to get used to something”): 職場に慣れる.
The second に (after の) is the “for (doing)” marker in the pattern V-のに時間がかかる: “it takes time for V.”

Why is 時間 marked with が and not を?

Because かかる is intransitive. The thing that “takes (is required)” becomes the grammatical subject with が. So you say 時間がかかる, お金がかかる, 手間がかかる. Saying 時間をかかる is ungrammatical.

Can I use こと instead of の here?

No; in this pattern you use の, not こと. Natural: 慣れるのに時間がかかる. Unnatural/odd: 慣れることに時間がかかる. The “for doing” meaning that pairs with 時間がかかる is expressed with V-のに, not V-ことに.

How is 慣れるのに時間がかかる different from 慣れるまで時間がかかる?

V-のに時間がかかる focuses on the resources required to perform V: “It takes time (money, effort) to V.”
V-まで時間がかかる focuses on the duration until the state/event V happens: “It takes time until one gets used to it.” Both are often interchangeable in meaning, but:
のに highlights the “cost” of the process.
まで highlights the endpoint and the time leading up to it.

Why is 彼女 marked with は and not が?

は sets 彼女 as the topic (what we’re talking about). It’s natural if she is already known in context: “As for her, it takes time…” If you use が with 彼女, you’re marking her as the subject of the subordinate clause 彼女が慣れる, often to introduce her as new information or to contrast with others.

Is this version okay: 彼女が新しい職場に慣れるのに時間がかかる?

Yes. Here, 彼女が is the subject of the embedded clause 彼女が…慣れる. The main clause still has 時間がかかる. Both

彼女は新しい職場に慣れるのに時間がかかる (topic-marked)
彼女が新しい職場に慣れるのに時間がかかる (subject-marked in the embedded clause) are natural; the choice depends on discourse focus.

Can I drop 彼女 altogether?

Yes: 新しい職場に慣れるのに時間がかかる。 That becomes a general statement (“It takes time to get used to a new workplace”), with the subject understood from context (I/you/people).

Does 彼女 mean “she” or “girlfriend” here?

It can mean either; context decides. In narratives or neutral descriptions, 彼女 = “she.” In casual conversation, 彼女 often means “girlfriend.” If ambiguity matters, specify (e.g., その人, or add context).

What tense/aspect nuance does かかる have here?

The nonpast かかる can express:

General truth/habitual: “She (generally) takes time to get used to new workplaces.”
Future expectation: “She will take time to get used to the new workplace.” Context clarifies which.

Can I say 慣れるのには時間がかかる? What does the は add?

Yes: 慣れるのに + は adds topicalization/contrastive emphasis to the whole phrase “as for getting used (to it).” Nuance: “As for getting used to a new workplace, that takes time (as opposed to other things).”

Why is に used with 慣れる? Could I use へ or を?

慣れる selects に for its target: Xに慣れる = “get used to X.” Using へ or を is ungrammatical in this meaning. Think of に as marking the state/situation you adapt to.

What other nouns commonly go with かかる?

お金がかかる (costs money)
手間がかかる (takes labor/effort)
費用がかかる / コストがかかる (incurs cost)
期間がかかる / 時間がかかる (takes time) Same pattern: V-のにNがかかる (It takes N to do V).

How do I make this polite or ask a question?

Polite:

彼女は新しい職場に慣れるのに時間がかかります。 Past:
…かかりました。 Question:
どのくらい（どれくらい）時間がかかりますか。 (“How long will it take?”)

Is there a difference between 慣れる and 馴染む?

慣れる: to become used/accustomed to something (broad, neutral). Pattern: Xに慣れる.
馴染む: to blend/fit in, to feel at home (more about harmony/affinity). Pattern: Xに馴染む. Both can work with 職場, but 慣れる is the standard choice for “get used to a workplace,” while 馴染む can imply “fit in well with the culture/people.”