Pea-sized retinol amount, is that enough?
A pea looks like very little cream for a whole face. The first question is whether that small amount is a mistake or the plan.
The amount a source gives
Yahoo's skincare guide gives retinol "A pea-sized amount" as how much to apply. The size is stated as the amount, so the small dab is the instruction and not a shortcut.

Why the evening comes with it
The same guide pairs the amount with a time of day, "In the evening". If you are used to applying more, the way to judge the pea is to follow both parts of that line for a while and notice how your skin responds.
Wider skin care reading
The Cleveland Clinic newsroom has Dermatologist-Approved Tips for Healthier Skin, and the AAD offers skin care secrets. Houston Methodist walks through a skin care routine for your 30s, 40s, 50s and beyond, and the Skin Cancer Foundation covers sunscreen.
Judging the pea over a few evenings
Keep to the pea for a few evenings and check how your skin looks each morning. Readers in St. Johns, Florida, who think the amount is not doing its job can raise that with a provider before increasing it.