as a rule
adverb
- usually; generally; ordinarily; used for saying what usually happens
Wiktionary
adv
- In general; most often.
“We go fishing every Sunday as a rule, but today the lake is frozen.”
“His forefathers had been, as a rule, professional men—physicians and lawyers; his grandfather died under the walls of Chapultepec Castle while twisting a tourniquet for a cursing dragoon; an uncle remained indefinitely at Malvern Hill;[…].”