The phrase "affect how often" is correct and usable in written English.
You can use it when discussing the influence of one factor on the frequency of another action or event.
Example: "The weather can significantly affect how often we go for a run each week."
Alternatives: "influence the frequency" or "determine how frequently".
But your exercise routine, body type and health conditions all affect how often you need carb-rich foods and how much of them.
This thesis sought to determine these perceptions and analyze how these perceptions affect how often 18-35 year olds use cellphones while driving.
Improvements in analytical methods may also affect how often substances are detected and at what levels, and therefore the resulting indicators.
The health of an individual is bound to affect how often and how long they are away from their place of work [ 16, 44, 46, 56, 59, 69].
The type of treatment dogs were administered with did not affect how often subjects were involved in social play (Wilcoxon signed rank test: z = −1.749, N = 15, p = 0.08), nor how often they engaged in play after receiving a play invitation (z = 0.479, N = 15, p = 0.6384).
The type of fluid will affect how often you need to change the patient's IV.
AV fleets are also expected to fundamentally change the way cars are used, affecting how often and where future vehicles will be parked.
Of those making $100,000 or more, 26% said money worries were affecting how often they were intimate with a partner.
Leveling up will increase his statistics: hit points, the amount of damage the character can receive before dying; magic points, which affects how often he can cast a magical attack; strength, the power of the physical attack; defense, the reduction of damage taken from an enemy; intelligence, the strength of the magical attack; and luck, which determines the rate of items dropped by enemies.
For example, 71 respondents (19%) said their cough affected how often they visited friends or relatives.
