Agreed with zaxjax. I take the plates off when I'm doing a full detail, very rarely for maintenance washes or even in-between waxing.
'15 i3 REX // Capparis // ZGW // ZTD // HK // 20"
20% Tint, Coding, LED High Beams/Signals, Painted Reflectors, MAX2 Hardwire
Past: F30 335i, E90 328xi