Yeah, I can see how you would have to go fairly long with the bonds to get a 5 year GIC ladder's weighted average maturity up to 7 years. My ladder's spreadsheet calculates all sorts of stuff such as weighted average maturity and duration as it use to involve mostly bonds, but I have gravitated to GICs over the years as they have become the best choice in the 0-5 year's ladder construction.The big lesson I learned with individual bonds is that you have to manage the weighted average maturity of your portfolio. XBB and VAB are at 10 to 11 years, but my bond portfolio is 7 years. I'm going to keep it at 7 years for a while and see how that goes. Note that this means I have to keep buying longer term bonds as bonds/GICs mature.
This is actually pretty challenging to pull off. The shorter maturities in my bond portfolio are mostly GICs (0 to 5 years) but to get the average up to 7 years, that means you have to buy some really long term bonds too!
With ladders exclusive to GIC's I have a weighted average maturity of 3.32 years today as I just renewed a couple rungs last month. That means if I wanted to increase the weighted average maturity to 7 years by purchasing bonds, I would need some fairly long maturity dates. I see why you're buying 30 year bonds.