Normally I wouldn't respond to a post so old, but there is a lot of misleading information here that could detract from others' growing experience. The spots are not related to a biotic pathogen or high/low light levels, and don't look like a manifestation of over-watering, under-watering, or a high level of dissolved solids (salts) in the soil solution. What it looks like is a response to a phytotoxic (poison to plants) product that somehow found its way onto the leaf surface. Examples would be inappropriate use of an insecticide or using a household cleaning product (Dawn/Ivory dishsoap, e.g.) to "clean" the leaves or combat an insect problem.
Additionally, habitually watering in small sips is a recipe for disaster, and watering on a schedule as opposed to on an as-needed basis ensures either over or under-watering and a build-up of salts in the soil that will eventually prevent a plant from taking up water. Think of how curing salts 'pull' water out of the cells of ham or bacon and you can see how the buildup of dissolved solids (salts) from tapwater & fertilizer solutions can quickly kill a plant - same mechanism - reverse osmosis. The technical term for this occurrence is plasmolysis, commonly: fertilizer burn.
Plants should never be allowed to sit in the effluent that exits the drain hole. The motive behind watering thoroughly is to regularly flush soils of salts that accumulate in the soil, out of the pot into the collection saucer. There should be no pathway by which the effluent can make its way from the collection saucer back into the soil. Best to water over the sink and wait until the pot is completely done draining, or lift the pot so it's well above any effluent that collects in the pot.
Example:
"Miracle-Gro Fertilizer" covers a lot of territory. Some MG fertilizers are 'ok' for Ficus, and others are wholly inappropriate. For example, the most common general purpose MG fertilizers (24-8-16 and 12-4-8) lack calcium, magnesium, and get all of their nitrogen from urea, which tends to produce coarse, rangy plants with long internodes and large leaves. Almost all houseplants respond very favorably to Dyna-Gro's Foliage-Pro 9-3-6, which has all the nutrients needed for normal growth and derives it's N from ammoniacle and nitrate sources.
Al
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