noun
intermittently; off and on; in fits and starts
Describes something that happens repeatedly over a drawn-out period, like early summer rain that comes and goes. Often used adverbially as 五月雨式に.
See also: 五月雨
彼からの返事は五月雨式に届いた。
His replies arrived intermittently over a long period.
五月雨
I'm sorry for contacting you repeatedly in bits and pieces.
五月雨 refers to the intermittent early summer rain itself, while 五月雨式 describes the manner or style of something happening like that rain.
断続的 is a more formal, general term for 'intermittent', while 五月雨式 carries a nuance of dragging on over time, often with a slightly negative or apologetic tone.
Compound of 五月雨 (samidare, 'early summer rain that falls intermittently') and 式 (shiki, 'style, manner'). The expression likens a drawn-out, stop-and-go process to the pattern of early summer rain.