Three young cactus or succulents in one planter

[StarDragon]

I know you generally don't want to pot a plant in a planter that is too large for the root ball, & why, but what about three, roughly three inch tall, young plants in a planter just large enough to where they have roughly an inch or 2 between the plants?

They will need to eventually be replanted either way, just from crowding after new growth alone. Is there a significant risk of root problems & other ailments from the pot size & number of plants before they put on new growth?

I realize cactus & succulent plants are frequently grown & sold in clusters in one planter, however, I know that may not be ideal. Retailers occasionally do things that are not ideal, as long as they are able to sell it.

[esp_imaging]

Provided the plants have similar care requirements and are similar vigour, this should be fine.
As you note, they will eventually need to be separated (and the roots untangled). There isn't any inherent risk of ailments (small seedlings are often kept together until they are really crowded), provided the container size, compost composition and watering regime are all compatible. A massive container, tiny plants, a water retentive compost and a tendency to over-water would be a poor combination, but it sounds like you may be clued up with these factors.
So why not give it a go, it could look great for a year or 2, until they get overcrowded, or possibly the most vigorous, fastest growing plant starts to take over at the expense of the others.

[StarDragon]

In that case, they should be fine. If any of them appear to be getting stunted prior to repotting time, I will remove them from the pot they share with the more vigorous plant & repot them. Yeah, I'm already clued in about the mentioned factors. The pot size is not huge, just large enough to give them some space & to where there is 2 or so inches below the roots. The compost is roughly the same for all, but one, but it just takes a little longer to completely saturate the soil during watering. It only totally plumps back up when I gave it a little more water than before. The watering regime is compatible for all, but two, but so far, I have been watering those a certain way to prevent either over-watering or under-watering, & have not had any problems. Thanks.

[greenknight]

Yes, it's usually a temporary arrangement - though I had one I kept together for quite a few years, transferring it to larger planters when it got crowded. Eventually one rotted, and I had to split it up. You have to take action quickly if that happens, before rot can spread to the others.

[StarDragon]

Yes, I'm mindful of that, even to the point where, in the past, I have nearly mistook corking for decay. Thanks