If the Opening Balance isn't correct, your register balance on any given day will never match the bank's balance on the same date and your register will never reconcile correctly.
* that's called a "transfer back into the same account" and is OK. Quicken uses this method to establish the Opening Balance without making it appear as an Income or Expense in any views or reports.
If you do decide to make or keep Balance Adjustments, they should be categorized same as the Opening Balance Transaction.
Transfer transactions between accounts (e.g., transfer Checking to Savings) should categorized using the account register name of the transfer to/from account, e.g., in register My Checking, a transfer to My Savings is categorized [My Savings]. This will create a linked pair of transactions, one in My Checking and the other one in My Savings. Uncategorized or incorrectly categorized unlinked transfers need to be fixed or deleted.