Raid is not the "worst thing" you could do to your plants. It is not labelled for use on house plants, or on plants outdoors, but it is basically a synthetic pyrethrum compound and a synergist to help compensate for the fact that lots of insects are already resistant to pyrethrum family compounds. The issue with using Raid on plants is the synergist, and the propellant are not designed to be safe for plant leaves. Tough plants like Hibiscus, as your mother had found out, are fine with the the Raid product, but delicate houseplants like ferns would likely be seriously burned by the Raid spray. Its quite possible much of the leaf drop is burning. With BRT leaf drop once or twice a year is no big deal.
It would be good to look for sprays labelled for use on plants. All the big box stores have spray pesticides that are specific for houseplants. You could also look into sprays that are labeled for the pests you most frequently encounter. Plant sprays will list any species of plants they should not be used on, and they will list what pests they will kill. If the pest is not listed as something the spray will kill, it is quite likely the spray will not kill that pest. So it is important to read labels.
But if what you have been doing works, who am I to say you must change.