The person who does the right thing habitually is more admirable than the one who manages to do it occasionally

"We are said to merit . . . in two ways.  First, . . . by merit itself . . . [i.e.] acts [(merit by meriting)].  Secondly, . . . by the principle by which we merit [i.e. act (merit by the power of meriting, i.e. virtue or habit)]."

"aliquo dicimur mereri dupliciter. Uno modo, sicut ipso merito, eo modo quo dicimur currere cursu, et hoc modo meremur actibus. Alio modo dicimur mereri aliquo sicut principio merendi, sicut dicimur currere potentia motiva, et sic dicimur mereri virtutibus et habitibus."

     St. Thomas Aquinas, Summa theologiae I-II.55.1.ad 3, trans. FEDP (i.e. Shapcote).  Latin from Corpus Thomisticum.