I do 50% WC's weekly on all my tanks, including my 220g heavily planted and have done this for over 30 years with excellent results. Larger WC's remove more ammonia if present and also keeps excess nutrients, dissolved organic and inorganic levels lower. Fish don't get stressed from a weekly large WC if it's done properly with temps matched properly. My plants and fish seem invigorated after these changes and often times spawning occurs the next day with several species.
Just curious, what are the size of your other tanks?
Her fish are dying, and ammonia is above 0, algae is rampant... and she's been doing 45% or so water changes frequently, so I think trying a different method to get things stabilized is worth a shot.
Doing larger WC with the EI method is one way to do things, but imho with smaller tanks, larger water changes can stress out the fish because you are changing parameters pretty drastically. Even if the water temp is the same, city water can have different nutrients and metals, and also includes co2 which does alter pH of the tank.
There are definitely many ways to do a tank, I've done everything from Walstad method to now dipping my foot into ADA waters. There are no right or wrong, just pros vs. cons. How much maintenace, time and money can you contribute as well as what types of plants and fish you want to keep all factor in to which method will work.
So, not saying that your method is wrong, but again I think maybe since this tank hasn't yet started fert dosing and is not stabilized yet, it is worth doing the things I suggested first to see if the ammonia spikes and fish deaths can be stopped.