I have this problem with my rue, that some of its leaves are yellow and weak. I tried watering less often and all the leaves became a little dry/crispy so I assumed it was not over watering. I live in a template area and right now there are about 24C (75F). The rue has roughly (I think) 5-6 hours of sun, maybe more. At first I thought that it was natural since it appeared more on the bottom leaves but now it's more proportionally spread. I'll appreciate any help, thank you.
The problem is most probably dehydration, since when you watered less, you saw more of yellow leaves and since the leaves of plants that are under-watered will be crispy with a slight curl to the leaf (same as shown in the image above) while over-watered leaves will be limp.
You are planting in a pot, so the pot's size, the size of drainage holes and the soil's structure may affect the water retention and the plant's water and nutrient absorption.
This problem also may be caused by nutrient deficiency (nitrogen), and a lack of soil fertility.
What I suggest is that you add some fertilizer, and you water frequently whenever you place your finger deep in the soil and find out that it is dry. Whenever you find that the pot is small, then it's time to transplant to a bigger one.