I only think that applies for accounts opened in the last 90 days and/or with limited assets. I have been a customer for years and have a substantial amount in my brokerage accounts with them and all my ACH transactions clear the next business day; rarely two business days.
The specific circumstance was that I initiated an external ACH transfer from a Schwab Bank Checking account, which pulled funds from a remote bank, there was a default 4 day hold.
I don't keep alot of money in the bank accounts, but have a non-trivial relationship on the brokerage side.
Other banks (Credit Union, Capital One) typically clear these in 24-48 hours. It's not a "deal breaker" for me, and Schwab is an awesome bank, it's just a gotcha that can be problematic in some circumstances. If you have a business and pull money from one account to another, etc your process needs to keep it in mind!