Found myself in similar situations in the past. My tentative solution was to maintain a corpus of resources for practice (beyond the usual suspects of implementing the standard data structures etc.), and hope that when the chance comes, 1-2 hours each day for a week before an interview would suffice. And when I do practice, I don't use a code editor, either paper or plain editor with no way to execute the code, simulating the (horrible) conditions of interviews as best as I can.
Obviously, this doesn't get you the benefit of being constantly drilled, but should provide some advantage. If you do care enough to get yourself a bigger advantage, maybe try to clear a few weeks before a round of job searching (if that's how you operate), then use those weeks for a few hours of practice each day.
Obviously, this doesn't get you the benefit of being constantly drilled, but should provide some advantage. If you do care enough to get yourself a bigger advantage, maybe try to clear a few weeks before a round of job searching (if that's how you operate), then use those weeks for a few hours of practice each day.