setting high value for wal_keep_segments

I am going to sync slave with my master which is almost 500 G. I am not using archive directory instead of I am using wal files for streaming. As it may take almost 3 hours, I am thinking of setting up 400 for wal_keep_segments where I have enough space available.

Without the space issue, could there be any other problem in setting up such high value for "wal_keep_segments"? As this is production, I need to confirmed.

Thanks.