Sooner or later everyone who studies this strategy asks the sharpest question in the room: why not skip the line of credit and just send extra principal payments to the mortgage? It's a fair question, and the fair answer starts with a concession. Extra payments capture most of the math. Every dollar of principal you retire early stops accruing interest, whether it arrived through a chunk or through a plain old extra payment.
So what does the line actually add? Three things. Weigh them against your own situation.
First, reachability. An extra payment sent to the mortgage is gone. The bank won't hand it back when your transmission dies in August. Money moved through a line stays borrowable, so you can attack the mortgage hard without feeling like you've locked the storm shutters behind you. People pay down more aggressively when they know they can still reach the money, and that behavior difference is real even though no spreadsheet shows it.
Second, the parking effect. Between chunks, your income sits in the line and lowers its average daily balance, which trims interest every single day instead of only on payment day. It's a modest effect on its own, and I covered the mechanics in The One Number That Decides Your Interest Bill.
Third, structure. A chunk is a commitment with a visible payoff arc. For some people, watching that number fall is the difference between a plan that runs for years and a resolution that fades by spring.
If none of those move you, then extra payments are your answer, and you'll do well with them. This strategy was never the only road to a paid-off house. It's a road with particular advantages for people whose real risk is stopping partway. The full mechanics live on the How It Works page.