Both are correct. There are multiple paths to upgrade if it's jumping quite a bit. If you go back to the support site, and check 6.4.6 -> 6.4.10, then check 6.4.10 -> 7.0.11, you'll get the same path the doc is showing.
It's more just a matter of personal preference which path to take. Personally I prefer just one step upgrade when go over to the next major version like 6.4 to 7.0. Because most of upgrade problems happen with those major version jumps. If it's one jump, you can go back to the previous version (older major version) by just swapping the boot pertitions from 2->1 or 1->2 without needing uploading the saved config file. So 6.4.6->6.4.8->6.4.11->7.0.11 would be my choice.
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