Keeping all your eggs in one basket when investing in property is a dangerous game. If you’re building up a property portfolio it’s best to keep your lending options open and not use the same bank for all of your mortgages.
Once you hit a specific threshold of lending a bank will change your risk profile and might start calling in your debts before you’re ready to pay. Using your revolving credit function to help with deposits on your new property investments is a tactic used by many property investors using borrowed money as deposits. It’s not a strategy recommended to everyone but it’s what a lot of the experienced property investors do to help with their cash flows and purchasing power.