Мы то и дело проверяем время сушки.

То и дело is a fixed idiomatic expression meaning repeatedly, again and again, every few moments, or constantly in the sense of something happening over and over.

So in this sentence it gives the idea that we keep checking the drying time.

A good thing to remember: it is an idiom, so you should not try to translate то, и, and дело separately here.

Not exactly.

• постоянно = constantly, all the time, more like an uninterrupted state or very regular repetition
• то и дело = over and over, every now and then, repeatedly at short intervals

So то и дело often suggests that the action keeps recurring, rather than being one continuous action.

For example, this sentence feels like:

• we check it
• then check it again
• then check it again later

rather than one uninterrupted process.

Проверяем is imperfective, and that makes sense because the sentence describes a repeated action.

Russian imperfective is used for:

• ongoing actions
• repeated actions
• habitual actions

Since то и дело already tells you the action happens again and again, the imperfective fits naturally.

A perfective form in the present tense would actually have a future meaning in Russian, so it would not work for this idea.

It can cover both, because Russian present-tense imperfective often includes:

• ongoing present: we are checking
• habitual/repeated present: we check / keep checking

In this sentence, because of то и дело, the sense is specifically we keep checking or we are repeatedly checking.

Время is the direct object of проверяем, so it is in the accusative case.

However, время is a neuter noun, and in the singular its nominative and accusative forms are the same:

• nominative: время
• accusative: время

So even though the form does not change, grammatically it is functioning as the accusative object.

Because сушки is in the genitive singular.

In Russian, one noun often modifies another by using the genitive case. Here:

• время = time
• сушки = of drying

So время сушки literally means the time of drying, which is the natural Russian way to say drying time.

This is a very common pattern:

• начало урока = the beginning of the lesson
• конец дня = the end of the day
• время встречи = the time of the meeting

The dictionary form is сушка.

Here are the forms involved:

• dictionary form / nominative singular: сушка
• genitive singular: сушки

So in время сушки, the noun has changed form because it depends on время.

Here it normally means the drying time — that is, how long the drying takes.

So время сушки is usually about duration, not a clock time.

If you wanted to talk about a specific clock time, Russian would usually make that clearer from context or by using different wording.

Yes, it could be omitted.

Russian often leaves out subject pronouns when the verb ending already shows who is doing the action. Since проверяем already means we check, you can say:

• Мы то и дело проверяем время сушки.
• То и дело проверяем время сушки.

Both are possible.

Including мы can add a bit of emphasis or make the subject more explicit.

No, Russian word order is fairly flexible, though some orders sound more natural than others depending on emphasis.

This version is neutral and natural:

• Мы то и дело проверяем время сушки.

You might also hear:

• То и дело мы проверяем время сушки.
• Время сушки мы то и дело проверяем.

These alternatives shift the emphasis:

• starting with то и дело emphasizes the repeated nature
• starting with время сушки emphasizes what exactly is being checked

But the original order is a very normal, straightforward choice.

Yes. Проверять is a broad verb that can mean:

• check
• verify
• inspect
• test

In this sentence, though, check is the most natural translation, because the object is время сушки.

So the idea is not that we are conducting a formal test, but that we are repeatedly checking how much drying time there is or whether the drying time has been reached.

It is not slang, but it is somewhat idiomatic and fairly conversational in tone.

You can absolutely use it in normal spoken and written Russian, but it sounds more vivid and natural than a plain, neutral adverb like часто or постоянно.

So it is common and useful to learn as a set phrase.