Laptop Battery Best Practice: Always Plugged or Unplugged?

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So with phone batteries, the experts tell you to run your phone battery down to zero percent before recharging as that will get you the longest life out of your battery.

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Not sure what experts you're talking about, but I don't think this has been true for a very long time. More than a decade, at least.

Modern charging circuits actually never top off your battery, nor do they let them run completely dead. "100%" is usually somewhere around 85-90% of the battery's actual capacity, and "0%" is somewhere around 10-15%. Lithium batteries last longest when they are kept near the middle of their capacity. I doubt you could extend the battery's life by keeping an eye on the charge much more than the charge circuit already does for you. It's just not worth the time and effort.

This

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So with phone batteries, the experts tell you to run your phone battery down to zero percent before recharging as that will get you the longest life out of your battery.

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That is absolutely not true for lithium ion batteries. Getting the most out of lithium ion batteries is complicated as essentially everything but sitting at a 40% charge reduces the lifetime.

The worst things for lithium batteries are deep discharge (below 25-30% remaining) and sitting on a charger. The float voltage keeps the battery hot and shortens the life.

For a lithium ion phone, if you want the battery to degrade as little as possible, keeping the battery charged between 30% and 60% are good practices. Don't charge it over 60% and don't let it discharge below 30%.