I'll usually skip any dosing the night before a water change. I particularly do this to let glut get out of the system just in case but that is just me.
My thought is dosing is maintaining ferts in excess so it doesn't matter when dosed for most of us. Possibly iron or micros dosing may - not sure.
For the fish I think dosing should be as regular as possible but in general a few days missed I don't find matters. But particularly for nitrates and if you have sensitive fish I wouldn't try to overdose a tank a lot to make up for say a vacation. There I run CO2 the same (or less) and turn some lights off so fert use by plants is reduced. That's just my tank that I've found over time works for me.
If you have someone come in I gather filling in say pill boxes works well. I had my daughter feed the fish last trip and I think the betta gained a few pounds lol.
Faster growing stem plants I find suffer in my tank without regular potassium dosing, the rest of the plants would probably not care for a week. I test nitrates and phosphates quite regularly and find my heavily planted tank is almost getting enough nitrates from fish, phosphate I need to dose a bit each week and potassium I pretty much spoon in dry ferts daily.
