Snapchat DM limits ?

Sometimes it seems like there’s days where you send 5k DMs and nothing happens and days where you send 5-10 DMs and your account gets “temporary locked”.

does anyone have any knowledge if there is an actual limit or is it just random?

I have done Sc marketing + offered Sc services for the last 2 years almost daily, but never had this problem at least because of Dming.
Make sure the account's email/phone number is verified, use the same device & ip's on the same account. Use aged accounts.