"as often as not" 是一个固定短语，表示某件事发生的频率很高，相当于：
通常；往往；多半；动不动就（强调“并非偶尔，而是经常性发生”）
它是状语短语，修饰整个句子或动词，说明动作/情况的频率。位置灵活，可置于：
1、 句首（需用逗号隔开）；
2、 句中（动词附近）；
3、 句末。
通过不同场景的例子，理解其具体运用：
1、 句首（引出高频情况）
As often as not, the bus is late during rush hour.
（高峰时段，公交车往往晚点。）
2、 句中（修饰动词）
She forgets her umbrella as often as not when it rains.
（下雨时，她多半会忘带伞。）
3、 句末（补充说明频率）
I end up eating takeout for dinner as often as not.
（我晚餐通常吃外卖。）
注意与 "as often as"（和……一样频繁）的区别：
He calls his mom as often as I do.（他给妈妈打电话的频率和我一样。）
He forgets to call his mom as often as not.（他往往忘记给妈妈打电话。）
与 "more often than not" 意思几乎一致（更常用），可互换：
More often than not, he arrives late to work. = As often as not, he arrives late to work.
（他上班动不动就迟到。）
总结："as often as not" 是表达“高频情况”的实用短语，适用于描述日常习惯、常见现象，口语和书面语都可使用。