Should pots sit in standing runoff?

No. Empty the tray within an hour or two, or set pots on risers inside it.

How much runoff is right?

About 10-20% of what you poured in.

Media

Name: Pot Drip Trays (4-Pack)
Brand: Budometry
SKU: drip-trays
Price: 24 USD
Availability: InStock

Stage: Every stage

$24

Fabric pots breathe, which also means they weep from every side. Trays keep that off your floor.

They are also a measuring tool: runoff volume is how you confirm you watered enough to move salts through the medium without drowning the roots.

Heavy plastic, sized for 3 to 7 gallon fabric pots.

Breathable Fabric Pots, 5 Gal (5-Pack)

Air-prunes roots for a denser root ball and no circling or root rot.

$38

Watering & Feed Mixing Set

Measure feed properly and water the root zone without splashing leaves.

$34

Auto-Watering Drip System (6 Plant)

Pump, reservoir, and drip stakes so a weekend away never dries out your pots.

$125

Should pots sit in standing runoff?: No. Empty the tray within an hour or two, or set pots on risers inside it.
How much runoff is right?: About 10-20% of what you poured in.