What's the point of a 5s delay between sending media?

[Arondy]

I've faced an issue of a slow upload, as I initially thought, but it turns out there is a 5s delay if you send media in several consecutive messages. Is it really necessary for the bot to have this delay? As far as I know, there is no floodwait for the bots in private chats.

Here is the snippet of the source code I'm talking about (if opt.SleepThresholdMs == 0 { opt.SleepThresholdMs = 5000 }):

Also, maybe it isn't supposed to sleep if you send a single album with <10 media?