Does the Metadata API checkOnly flag preserve session state during incremental deployment of small Salesforce applications?

The objective is to evaluate whether Salesforce Metadata API checkOnly flag combined with incremental batch deployment can migrate a small application without interrupting active user sessions. This assessment must account for API version alignment between source and target orgs, and the extent to which dependent metadata types are validated during partial component updates.

Key constraints include potential performance overhead from re‑validating records under concurrent traffic, and the degree to which batch sizing influences session continuity. Uncertainty remains around whether checkOnly previews accurately reflect deployment outcomes when multiple object types, Apex classes, or page layouts are updated sequentially.

Can the checkOnly flag fully validate dependent metadata types before a batch deploy? Which batch size thresholds minimize session disruption while preserving deployment speed? What version‑incompatible metadata types must be excluded or filtered in incremental pushes?