Always make sure that that your string players have plenty of time to put on and take off their mutes. Yes, this is a standard caution of orchestration manuals, but there’s more to it: you also have to provide some cover for the minuscule bustle as the players go about the process. Most players have rubber mutes sitting below the bridge that can be adjusted almost immediately. But that is for their purposes, not necessarily for yours – they are trying to cope with all the composers who are careless, but it’s not a license to kill for the rest of us…

Strings Mute Changes tip
excerpt from my harp concerto movement 3 in progress

That’s a stacked chord of all 7ths – essentially an open 13th chord spanning nearly 3 octaves. It’s a neat effect, but may be tricky to tune for my semipro doctor players… they’ll sort it, though!