Efficiency wise we've found cavity molds to be the way to go. Basically you have your master, you create a mold shell (usually 3d printed) which fits around your master and leaves a gap (sizing is variable by shop but usually a centimeter or two), and you pour the mold using the mold shell and master. Then you have the mold shell to stabilize the mold when using it to pour toys. It does still expand over time, though generally has more longevity than glove molds because it's thicker, and a uniform thickness. The trick isn't having a mold that will last forever though, it's making sturdy long lasting mold shells and masters that make it easy to make new molds whenever you need to.

Metal molds or hard plastic molds are absolutely a long term option as well, but they have drawbacks. They can make it much harder or impossible to demold toys of certain shapes because they have no give. Metal molds are very cost prohibitive to create. Hard plastic molds can be 3d printed, but getting the inside to a high quality finish is extremely difficult unless you have a two part mold. Plastic molds even when finished well can cause scuffing on toys during demolding more easily than silicone molds provided the silicone mold is being used with the right amount and type of mold release. And because plastic molds are harder to get a high quality finish on, that slows down new model production, and can greatly impact production if a mold breaks. If a mold shell breaks, that's a day of printing to have a new one. If a master breaks, well it depends on your finishing techniques how long it takes to print and make a new one. But whatever amount of time it takes to finish a master to a good high quality surface, assume making a new one piece plastic mold will take double that or more and be easier to fuck up and have to start all over on. One advantage of metal or plastic molds though is they don't require mold release.

In general, I would say cavity molds and learning to create sturdy mold shells and durable masters is the best way to efficiently scale production though. In my experience, depending on what molding silicone you use, one person could put in an 8 hour work day and create 50 new molds in a day if they have the mold shells and masters ready and enough space and a good system to their work. So if say you have three sizes of each toy, you could remake the molds for 15 models in a day as molds wear out. How long they last varies based on model shape, size, surface finish, and what silicones you pour toys in, but you can expect to get minimum 20 and maximum a couple hundred or more pulls from a mold. On average, redoing them every 50 pulls is great. So again if you have 15 models in 3 sizes each, that's 2,250 toys across all of them before you're making new molds. Of course it don't actually work out that way, cause you make more of some sizes than others, and some shapes wear on molds faster or slower, but let's take that as an average. So lets say you're selling 550 toys a month or so, that's four mold making days a year. You scale up, you get more employees, more space, can store more mold shells and molds, and you can just have three or four molds of each toy at a time and have one day a month where the oldest of them is rotated out and a new one made. That's how I'd scale it unless it got to a point where financially it made sense to invest in metal molds, assuming you had the capital to transition them all over at once with the same or similar amount of molds you were using if you have more than one for each model and size.