At most agencies, not the people who pitched you. The industry is priced on utilisation, so senior staff win the account and it then moves to whoever has capacity. This is the default, not an aberration, and it is the single most reliable predictor of how an engagement goes.
Ask for the name of the person who will touch the account every week and what else they are running, and get it in writing. At Kando one named senior operator runs the account — daily pacing checks, the weekly optimisation pass, the monthly review — with a co-founder on the quarterly channel-mix and transfer checkpoints.