Per 
What is a List Canon?
You might agree that there aren't 5000 SCP's roaming around any one SCP Foundation universe. List Canons are sets SCP's for one SCP universe.
One 001 Proposal
Thaumiels to support the setting, or none at all.
Few Keters
10 or so Euclids
Assorted Safes
2-4 Groups of Interest
These are rough guidelines. It's more about what is plausibly contained in one SCP Universe, or what gives it a coherent theme without being convoluted.
Examples
Abrahamic SCP
GOIS: Foundation, GOC, ORIA, Horizon Initiative
Tech: Amnestics
SCP-001: Gate Guardian.
SCP-073
SCP-076
SCP-1348
SCP-1983
SCP-1782
Classic SCP
Time Period: 50's-80's
GOIS: Foundation, Serpent's Hand, Chaos Insurgency, The Factory, GOC
Tech: Telekill, Amnestics, "Titanium"
SCP-001: The Factory / Spiral Path
Notable Characters: Old Guard Doctors
All Heritage Collection SCPs
Second Wave SCP
GOIS: Foundation, Serpent's Hand, Chaos Insurgency, The Factory, GOC
Tech: Amnestics, Deus Ex Machina, Reality Anchors
SCP-001: Wrong Proposal/Sheaf of Papers
Notable Characters: Tilda Moose, Scranton, Glass
SCP-1000
SCP-2000
SCP-3000
Assorted 2000-4000 Notables
Triumvirate SCP
SCP-001: Apotheosis
GOIS: Foundation, CotBG, Sarkicism, Maxwellism, Fifthism
Tech: Amnestics
Selected GOI specific SCPs
New Wave SCP
SCP-001: The Foundation/A Record
GOIS: Foundation, GaW, AWCY, Parawatch, Oneiroi, UiU
Tech: Amnestics
Selected GOI specific SCPs
