goodbirb

802.11r is pretty important, it's what allows the phone to skip the slow 4-way handshake when transitioning to new BSS.

A red flag for the author's trustworthiness, if ever there was one.

Each take about 10msec airtime (beacon+various broadcasts+probe responses+acks etc NOT including actual client data). (simplified)

Beacons repeat every 100msec. So you're already wasting up to 40/100 of airtime for management/misc frames

Wifi is a shared half duplex medium

Some new form of mystic numerology/gematria-based investment logic?

99% of what he did is not needed. Only 2 things are needed: enable fast roaming (FT), and change DTIM from the openwrt default of 2, to 3. That's all. No need to install usteer, extra hostapd fields. Nothing.

By lucky chance, while he set up usteer, he modified DTIM to 3 thus fixing the fast transition roaming, which doesn't work well on default openwrt because of DTIM. Especially Apple devices really hate DTIM=2 (they need the extra off-time given by DTIM to properly scan the other channels).