I am currently using daily dosing of Excel in three of my four tanks. Never had any problem doing this! I am very happy with plant growth. I LOVE the stuff!
These tanks are my smaller tanks with medium light and what I think of as a hybrid, medium tech tank. My aim with these tanks is more stability with medium growth for lesser maintenance tanks. Except for topping off, I do monthly water changes. (My fourth is a 75g with pressurized CO2, high light, lots of stems, EI dosing w/ weekly H2O changes....lots of work.)
HOWEVER, I did learned my lesson in the beginning, now I clearly understand proper dosing levels and how much is 5ml compared to teaspoons etc. I would GREATLY recommend you do not use the cap to measure doses! I purchased a medicine dropper at Wal-Mart that has ml on it. Cost only around $2.00. For my 35g tank I dose 3ml per day. And for the 46g ...I dose 4ml per day. I also purchase it in the larger jugs and not the small 250ml bottle so it is not as costly to use.