Learn Italian alone or with a teacher?

What works perfectly well alone

Vocabulary. Good spaced repetition beats any lesson: no teacher can bring a word back at the right moment better than a system that counts the days.

Basic grammar. The rules are written down, the exercises mark themselves, and there's one right answer. Paying someone to explain the present tense is money badly spent.

Listening and reading. There's more material than you'll ever use, and progress measures itself: either you understand more or you don't.

What you can't learn alone

Speaking. It isn't a matter of willpower: producing language in real time is a separate skill, and it's trained only by producing it in front of someone who answers. Someone who studies alone for three years and then can't order a coffee didn't study badly — they trained something else.

Knowing what you're getting wrong. Systematic errors are by definition invisible to the person making them: if you knew it was wrong, you wouldn't do it. You need outside eyes, and you need them early, because an error repeated for a year becomes a habit that costs twice as much to dismantle.

Knowing what to do next. The moment most people quit isn't when the language gets hard, it's when it stops being obvious what the next step is.

When it's worth paying

Not at the start. From zero to A2 the free material is plentiful and genuinely good, and a teacher there is doing work you could do yourself for nothing.

From the point where you have to speak. Typically upper A2: you understand a lot, you know plenty of words, and you notice none of it leaves your mouth at the right speed. An hour a week with a person changes more there than ten hours of exercises.

And before an exam, if you're taking one. Certifications have a strict format, and preparing blind is the most expensive way to save money.

What works best isn't one or the other: study alone during the week, and spend the hour with a teacher on the one thing you can't do alone — speak, and be corrected.