I just have a calendar that hangs on the wall. I write h2o for water, fert for fertilizer, e salt for epsom salt. I can see the current month and can tell what my plants need. They all get the same treatment at the same time. They grow well enough to please me so I am happy with this simple tracking. I won't have any special needs plants or they would die.
I also write the repot date on the tag. With time I have become able to keep the watering schedule in my head. Of course if you have hundreds, that maybe less do-able (I have about 100). Flush all at end of month.