No — not on raw cost per lead alone. In Gulf lead-generation accounts, cost per lead and lead quality are frequently inversely correlated: the market delivering the cheapest leads is often delivering the worst ones, while the expensive market is the one your sales team actually closes. Optimise to CPL and the dashboard turns green while pipeline quietly dies.
Optimise instead to cost per qualified lead, customer acquisition cost and payback period, which requires a CRM feedback loop so the ad platform learns from what sales did with the lead rather than from the form fill. If a client insists CPL is the KPI and there is no feedback loop to correct it, that is a legitimate reason for an agency to decline the work.