Rule of thumb.
Rule of thumb.
'Rule of thumb' refers to an easily remembered guide that is not necessarily precise but provides general instruction. This idiom originated from old craft practice, possibly derived from using the thumb as a rudimentary measurement tool. It's applicable in everyday situations where a full, detailed accuracy isn't necessary, allowing quick assessments or decisions.
By rule of thumb, he always starts his day with a jog.
He follows a general principle of starting his day with a jog.
It's a good rule of thumb to save at least 20% of your income.
It’s a good general practice to save at least twenty percent of your income.
Using the rule of thumb, she divides her work day into focused 45-minute intervals.
Using a general guideline, she segments her work day into focused 45-minute periods.