How important is LUKS reserved block count for external drive?

I have LUKS FDE on my external data HDD but recently almost filled it up. When cleaning it up I noticed that the available and free counters don't match. Read that LUKS reserves 5% of total capacity for "root user and system processes" and that reducing it could lead to loss of data. In my case that takes up 250GB of space on a 5TB HDD. What I want to know is what and how important of a role this plays and what is the minimum reserved space that is needed in case of external HDDs (that doesn't have bootable partitions). Does reducing the reserved blocks significantly increase the risk of data loss or make it non-mountable? I want to find a good balance between data safety and disk usage. Edit: Found this answer : https://unix.stackexchange.com/questions/334526/clearing-reserved-space-in-a-luks-encrypted-volume which speak of reducing to 1GB (0.3% of capacity) for a backup drive. Is that safe or does that pose any significant risk of data loss ? I was planning to let 0.5-1 % if that is acceptable.