Clarification: Are scheduled disruption budgets cumulative or concurrent for the specified duration?

[abhaytambe24]

Context

I am attempting to throttle Drift disruptions using a scheduled budget. My goal is to allow a total of 2 nodes to be disrupted due to drift during the first 5 minutes of every hour, and block drift entirely for the remaining 55 minutes.

Here is a preview of the budget

spec:
  disruption:
    budgets:
    # Allow 2 drift disruptions during the first 5 minutes
    - nodes: "2"
      schedule: "@hourly"
      duration: 5m
      reasons:
      - "Drifted"
    
    # Block ALL drift disruptions for the remaining 55 minutes
    - nodes: "0"
      schedule: "5 * * * *"    # Starts at :05 each hour
      duration: 55m
      reasons:
      - "Drifted"

The Issue

Expectation: I expected Karpenter to disrupt a total maximum of 2 nodes during that 0–5 minute window.

Observation: I am seeing Karpenter disrupt significantly more nodes (between 5–10) within that same 5-minute window. It appears to be treating the nodes: "2" limit as a concurrency cap rather than a cumulative limit for the duration of the budget window.

Question:
How is the nodes value in a disruption budget intended to function when a duration is defined?
Is it a cumulative limit (once 2 nodes are disrupted, no more disruptions occur for the rest of the 5m window)?
Or is it a sliding/concurrent limit (Karpenter ensures no more than 2 nodes are actively being disrupted at any single moment, but will move on to the next batch once the first two are gone)?