Independence is what makes the chain worth more than one link
An approval chain requires a request to pass through a sequence of separate sign-offs, each performed by a different party, before it proceeds — a purchase requiring both a manager's approval and a separate financial reviewer's, for instance. The entire value of adding a second link beyond the first rests on that second approver exercising genuinely independent judgment, catching something the first approver might have missed, rather than treating the first approval as sufficient reason to add their own signature without real scrutiny.
A chain where every subsequent approver defers reflexively to whoever signed off earlier isn't actually providing multi-level review — it's a single effective check, dressed up with the appearance of several, and it costs more time and friction than a single, honestly-labeled approval would without providing any of the additional scrutiny multiple approvals are meant to add.
The chain needs a plan for when a link is unavailable
An escalation path defines where a stalled request routes when its designated approver is unreachable, rather than leaving it stuck indefinitely. Without one, every single link in the chain is a hidden point of total failure — any one absent approver can stall an otherwise urgent request regardless of how time-sensitive it actually is, which makes an explicit, pre-planned escalation path as essential to the chain's real-world reliability as the approval logic itself.