To reduce the amount of MetaMask calls for Applying Domains, you may enter the amount of adToken you want to pre-approve in the Pre-Approve ADT Transfer section located within the My Dashboard.
Pre-Approve ADT Transfer section
Note* Pre-approving adToken for Applying Domains DOES NOT withdrawal adToken from your account, it simply grants the adChain Registry dapp the authorization to withdrawal adToken so that when you decide to Apply a domain, MetaMask will only call the adChain Registry Smart Contracts for that specific action. This reduces the amount of MetaMask calls and gas fees that you pay overall.
Pre-approving adToken for Applying Domains should only be used if you plan on applying multiple domains to the Registry.