каждые среды
каждые воскресенья
I noticed that you made this mistake more than once. But in fact using "каждый" + noun is not that hard, it works the same way as in English.
every Monday - каждый понедельник (
sing., you don't say "every Mondays", do you? Ot may be in English you do, I'm not sure
)
every week - каждую неделю (
sing.)
every two days - каждые два дня (
plural, "каждый" refers here to the "packs" of
two different days)
every few months - каждые несколько месяцев (
plural, the same reason)