You're lucky you didn't melt the Vals but glad it's working for you & your plants. Vals are sensitive to Excel/Glut. You usually need to work up to full dose when you have sensitive plants like that. Maybe they got desensitized the few days you used Excel.
Not sure how everyone else does it but I never do the initial dose or extra-large dose after water changes. I don't want to take a chance of melting sensitive plants even though I've been dosing several months now. Seachem really needs a statement on their bottle about sensitive plants and how to dose .. it's only on their website they mention not to do the initial high dose.