Although not a FCP tip here's something I noticed today that may save people's sanity on-set. On an H4N Zoom audio recorder, after a while tapping the REC button will take a long long time to begin monitoring audio, and sometimes it'll go straight to recording (this is with Firmware 1.72).
The solution I discovered was to simply tell it to record into an empty folder. That seems to eliminate the excruciatingly long pause before it starts rolling.
There must be some sort of file or file-tree check before it begins writing or thinking about writing to a card with many files on it. Today was with a Class 10 card so it's likely not a speed issue. My guess is somewhere around 100+ files causes a slow down to turn on monitoring/recording.
So by recording to an empty folder there's no file-tree to check and it goes right to monitoring/recording. New rule: New Day - New Folder.