There's various online fatawa around which describe the effect of urinary incontinence on salah prayer (e.g. IslamWeb 1, 2; SeekersHub; Zamzam Academy; MuftiOnline 1, 2, 3; Islam Q&A 1, 2, 3). They usually state that ablution (wudu) is required before each salah, and should be performed after the time for prayer has started. However, they don't seem to address this question:
Question: Does a Muslim woman with urinary incontinence need to change her pad before each prayer?
A woman with urinary incontinence may absorb the urine using some kind of pad, which will be kept against her skin. (Maybe men with urinary incontinence do the same, I'm not sure.) However, the pad may or may not be enough to keep the impurities away in order to perform prayer. Obviously, there's a level of impracticality to changing a pad this many times per day.