Here's a list of typical restrictions you might come across.

NFTs minted at once

Unique API provides a method for minting multiple NFTs in one transaction; for bare API - unique.createMultipleItemsEx, or using SDK - sdk.token.createMultiple. However, there is a limit for a block weight which could lead to 1010: Invalid Transaction: Transaction would exhaust the block limits error.

The safe limit is 35 NFTs minted at once.