If you are not experiencing performance issues then it’s not very important for you.
Defragmnenting a drive rearranges files on the drive so that each file is written contiguously as opposed to being written in fragments all over the disk.
Fragmentation makes the computer work much harder in reading a file back and in video editing that can cause stuttering during playback.
It’s not a bad idea to put the defrag on a weekly schedule and let it run overnight.
Cheers
Eddie