I would introduce a proper circular (ahem) route around Walthamstow,
rather than relying almost solely on longer distance routes to provide
service, particularly off the north south corridor.

For instance, the 158 bus that runs up from Stratford-Leyton over Lea
Bridge Road (major cause of delays) - then past Kelmscott
School/Leisure Centre, St James Street Station - Blackhorse Road
Station - down Blackhorse Road the Crooked Billet roundabout (more
delays) then Chingford Mount (past Walthamstow Dogs - more delays) is
the only bus up Billet Road from Blackhorse Road, and is always
heaving. A more sensible suggestion would be a bus from Walthamstow,
down to St James's Street, up Blackhorse Road, round the Crooked
Billet, and back to Walthamstow.

LRT (as it was then) did something similar with the W11/W12/W15 routes
and these buses are also stacked to the gills despite operating up to
every 10 minutes.