I've been doing the same here in Texas (moving the containered plants close to the house under the overhangs, to keep them from getting soggy). As to whether it is okay or not probably depends on the plant, and how much water they still get - even if somewhat covered. I notice that mine still get watered, I suppose because the winds sometimes blow the rain at an angle. You might do some research for each plant (maybe online) as to watering, especially regarding soil staying moist. I've drilled holes in all my containers to make sure they drain well. The containers - as bought - never seem to have enough drainage, in my opinion. I only grow vegetables and herbs, but tomatoes (for example) need good drainage. Hopefully someone else will add to the conversation, especially about marigolds and such.

Old timers watched walnut trees and the first appearance of mouse ear-sized walnut leaves meant no more plant killing freezes. I laughed a couple of decades ago when an aged neighbor told this to me; but so far our walnuts are better predictors than our weathermen.

I've been interested in the genus Pandanus for quite some time. They used to be commonly available as houseplants but became positively rare in the trade. I think it was because most species have spines (and those can cause minor dermatitis on most people). I used to grow Pandanus 'Veitchii' (which has nice creamy white variegation) and was probably one of the very few few variegated plants I preferred over all green ones. Ended up giving multiple pups away but somehow, over the years, lost the original mother plant. It does not surprise me that they do well in containers as you have excellent soil drainage (potentially). So, make your your soil has good drainage (soil you might use on palms or cycads for instance). They are not tolerant of cold, wet soils..., maybe add a generous amount of coarse sand and/or perlite. I see you are in SF; I am not sure how the plant will grow in that climate. (I I would put mine out in the growing season but have to take mine in for frost..., still, it got really, really BIG. Actually, too big for an average house if only in the Winter!) You can experiment with yours..., just try to propagate it by taking pups that show evidence of roots. P.S., Currently, I am growing P. amarylifolius (pandan plant); used in SE Asian cuisine..., and the only species of Pandanus used culinarily. Has the typical stilt roots of the species but without the spines and variegation of the 'Veitchii'.

Most "store-bought topsoil" I've seen has been black sand with a small amount of OM mixed into it, and has served poorly in any application where it's been pressed into service as a growth medium or a part thereof. In order to get topsoil to work in containers, (for the sake of accuracy) you'd be better to say that you'd need to add a small fraction of the topsoil to a large fraction of the calcined DE you mentioned to come up with an overly water-retentive medium that's very unlikely to work for conifers or any other plants using the methods commonly associated with conventional container culture. Please allow me to explain: If you have a quart jar half full of topsoil (a pint) that supports 4" of perched water, and you mix in a pint of calcined DE screened to 2.5mm (roughly 1/10") to 5mm, what do you have in terms of an improvement in aeration or drainage? Since the volume of topsoil is more than enough to fill every air space between the DE particles, you still have a medium that supports just south of 4" of perched water and virtually no increase in aeration or drainage. Change the mix so you have a 60/40 mix of DE and topsoil, and what do we have? About the same thing, but with a slight decrease in the ht of the PWT - aeration/drainage remains about constant. It's only when you've increased the volume of DE to the threshold point where there is no longer enough topsoil to fill the air spaces between the DE particles that aeration/drainage starts to increase with any significance. If you have 80% DE and 20% topsoil, it's hard to suggest you're amending the topsoil with DE, the equivalent of saying you add coffee to your cream. Even if you had 100% screened DE 2.5mm-5mm, you'd still have a medium too water-retentive to keep an overwhelming % of plants happy. If you need to lower pH for container media, one would use an acid-forming fertilizer, or acidify the irrigation water. Adding S to acidify and 'some micronutrients' sounds to me like a recipe for problems. A fertilizer like Foliage-Pro 9-3-6 is an acid-forming fertilizer that has ALL the nutrients plants normally get by the root pathway, in a ratio that closely matches the ratio at which the average plant actually absorbs nutrients, and in an appropriate ratio to all other nutrients in the solution. IOW, the average plant uses about 6X as much N as P, and about 3/5 as much K as N, and that's reflected in the NPK %s of FP 9-3-6. Al