Larger producing plants may require watering two or three times a day. Also remember that a porta-plant can shade itself and should be rotated periodically to insure exposure of the entire plant to the full sun condition so that uniform foliage and fruit formation will occur. If a foliage plant or flowering plant such as begonia requires a partial shade growing condition, putting such a porta- planted plant in a full sun condition dooms it to failure. Follow plant tag recommendations for light requirement. Generally, those plants which produce an edible fruit such as tomato, pepper, eggplant, blackberry, peach, apple, etc., require the full-sun condition.
Flowers have different requirements depending on the kind.
Placement of porta-plant containers is also very important. Even if a plant requires a full-sun condition, afternoon shading of the intense western sun may be beneficial. Also remember the wind. Wind can be devastating. I have found that a northeastern exposure, if available, is the best because of the protection it allows from prevailing strong southern winds and hot evening sun.