Se metti troppo balsamo, ci vuole più tempo per risciacquare.

It can absolutely be general. Italian often uses the informal you to state general truths or give practical advice, much like English if you put too much conditioner....

If you wanted a more impersonal version, you could also say Se si mette troppo balsamo...

Because balsamo is being treated as a mass noun here, like water or sugar in English. After words like troppo, Italian often uses the noun without an article:

• troppo balsamo = too much conditioner
• troppa acqua = too much water

If you added an article, the meaning or tone would change.

Here balsamo means hair conditioner.
The word can also mean balm in other contexts, but in hair-care language balsamo commonly means conditioner.

It is a masculine singular noun: il balsamo.

Ci vuole is part of the expression volerci, which means to be needed or to take in the sense of time.

So:

• Ci vuole tempo = It takes time
• Ci vuole più tempo = It takes more time

In this sentence, it means that more time is needed to rinse.

In volerci, the ci is part of the fixed expression. It does not literally mean there or us here.

So it is best to learn:

• ci vuole = it takes / is needed
• ci vogliono = they take / are needed

Think of volerci as one unit.

Because the verb agrees with più tempo, and tempo is singular.

• Ci vuole più tempo = More time is needed
• Ci vogliono più minuti = More minutes are needed

Even though più means more, the noun tempo is still singular.

Because tempo here means time as an uncountable idea, just like in English.

• più tempo = more time

You would only use tempi in other meanings, such as historical periods, times in a broader sense, or certain set expressions.

Per + infinitive is a very common way to express purpose or the action something is needed for.

So più tempo per risciacquare means more time to rinse or more time for rinsing.

This is a very normal Italian structure:

• tempo per studiare = time to study
• qualcosa da mangiare is different, but also an infinitive structure learners often compare

Italian often leaves out the object when it is obvious from context. Here, everyone understands that the sentence is talking about rinsing out the conditioner or rinsing the hair.

You could make it more explicit, for example:

• per risciacquare i capelli
• per risciacquarlo

But the shorter version is completely natural.

Yes. A very common alternative is:

Se si mette troppo balsamo, ci vuole più tempo per risciacquare.

That version sounds more impersonal, like if too much conditioner is applied or if one puts too much conditioner.

The version with metti sounds more direct and conversational.

Because this sentence expresses a real, general condition: if this happens, this is the result.

Italian commonly uses:

• se + present, present for general truths
  
  • Se mangi troppo, stai male.
• se + present, future for likely future situations
  
  • Se mangi troppo, starai male.

So Se metti troppo balsamo, ci vuole più tempo... is a normal present-tense pattern for a general fact.

It is very common and natural to put a comma after an initial if clause in Italian, just as in English.

So:

• Se metti troppo balsamo, ci vuole più tempo per risciacquare.

is the standard written form. In very short informal writing, people sometimes omit it, but the comma is the safer and more natural choice.