While discussing the laws of the sabbatical year, the Torah warns us that even the plants which have grown of their own accord are not to be benefited from.
In Leviticus 25:5 the text says, “אֵ֣ת סְפִ֤יחַ קְצִֽירְךָ֙ לֹ֣א תִקְצ֔וֹר וְאֶת־עִנְּבֵ֥י נְזִירֶ֖ךָ לֹ֣א תִבְצֹ֑ר”. You shall not reap the aftergrowth of your harvest or gather the grapes of your untrimmed vines. Tur HaArocj explains this verse as follows, “The land enjoys freedom from its owners during that year, i.e. it enjoys a שבת שבתון. Man and beast enjoy what there is to enjoy alike.”
The writer is also a sort of farmer. Some of the produce comes from the constant process of thinking and planning, researching, analyzing, and actual planning. Just like agricultural work never ends, the writing work is never finished. The projects are ongoing and even when something is done and dealt with, the piece of land, aka the part of the brain it was growing on is never left alone to fallow.
Which, in all honesty, it should be. The creative resources just like the land ones are not endless. Even Shabbat does not help much since one can still read and think. However, the concept of shmita year can help the writers as well. The Torah commands us not to reap even something that has grown on its own accord during this year. We may enjoy them but we should not gather them in the usual manner of harvest.
So the writer, just like the land, can just be at that time. If some thought appears on its own accord, leave it alone. You can enjoy it later or it can go away. This is not important, since your creativity needs the rest just like the land does.