There is no single answer because monitoring frequency is tailored to your situation. People with type 1 diabetes or those on insulin typically check more often, including before meals, before bed, before driving, and when unwell. People with type 2 diabetes managed by lifestyle or medicines that rarely cause lows may need fewer checks.
Continuous glucose monitors (CGMs) have changed routines for many people by giving readings throughout the day without repeated finger-pricks, but they are not right or available for everyone.
Checking more often is useful during illness, when changing medication, when exercising more than usual, or in pregnancy. Because over-checking can cause anxiety and under-checking can miss problems, agree a clear plan with your doctor or diabetes nurse rather than guessing.