I fell into a discussion with two of my students yesterday about the point of studying grammar. Not that they were in any way opposed. Both were clear that they were here in Cambridge precisely to make a study of it. It was central to their programme.
They are high-level students who speak both fluently and on the whole accurately, and when pressed stated that what they most desired was to eliminate mistakes.
I pointed out, as any good teacher should, that perfection is not a realistic goal. Native speakers do not attain it. It does not exist. Structure and semantics are fluid and negotiated and mistakes often just indicate character and personality. I have a student who says a lot of lot of for emphasis. As in, there were a lot of lot of people in town last Saturday. It is wrong but clear, and I do not know anyone else who says it. I have another, a Russian, who qualifies every adjective with absolutely. It was absolutely warm yesterday afternoon. We have talked about why it is wrong, the distinction between gradable and non-gradable adjectives, but the habit is there and it is no bar to fluency or understanding. It is just characteristic of her very fluent English.
I further pointed out that the true goal of learning grammar should always be to increase range of expression. If you cannot use a third conditional it is going to be difficult to express counter-factuals in the past. If on the other hand you make a slip with a third conditional, throw in a stray would for example, no one will really notice.
But none of this really helps in the end. They know it is true, and yet they still do not want to make mistakes. I am the same. I feel like an idiot if I open my mouth and inaccuracies stream forth. Making yourself understood is not the goal: a lethal pinpoint semi-automatic delivery is the goal.
The answer, in the end, is balance and proportion. Dull, but true. Anyone will have good days and bad days. If you are already fluent by most standards then you are obviously doing something right. If you need to write contracts in your target language you will need to pull out the stops on the grammar. If you want English for making good presentations you might do better to focus on delivery and intonation, and let the grammar hang a little. Some details you will remember. Others will not stick. In the end, you will go to your grave a mass of imperfection, having somehow anyway achieved a great deal.