As far as swarm prevention goes its a constant battle, but in a sense I've come to look at swarming as an indication of good strong healthy colonies-- just bees following the natural world's primary edict: survive and reproduce. We lose swarms, theres no way around it, there just aren't enough hours in the day/week/month during the critical period (oct + nov here) to do enough to stay out in front of everything.
I would characterize our swarm control methods as both proactive and reactive. To limit the desire to swarm we requeen annually in the autumn. We've transitioned from Italians to Carniolans, finding the carnis to rebuild population faster if a swarm does go. We split a lot of 2X deeps into 1X deeps in the autumn which helps us stay out in front in the spring. Early spring the 1X hives gets a box of foundation and 5L syrup, a few weeks later we'll check on them and feed again as their drawing progress and the natural flow dictates. A few weeks later they get a medium added and they go into kiwifruit shortly after that where they get fed (3X 2L over 6-8 days) to increase pollen foraging. A constant supply of foundation to draw leaves them plenty of space and seems to occupy the hive mind with something beside reproducing.
The 2 inspections I mentioned previously were referencing formal disease(afb) checks. During the spring any time a hive is opened a couple brood frames are pulled to quickly check for swarm cells and get an idea of total brood frames. If swarm cells are found, each frame is pulled, bees shaken and swarm cells cut out. If we happen to see the queen in this process, we'll cage her and plant a new queen in the hive. A frame or 2 of brood can be taken from these powerful hives to boost weaker yardmates, and the position is swapped with weaker hive to balance populations. Because each hive needs to be up to standard for pollination we focus on evening out yards so they're all well above standard without blowing themselves apart. Time consuming but effective for our purposes. There's good arguments to be made for both balancing colonies, and letting your strong ones go full speed, while the weak ones stumble along, just depends on your preferences, purposes, and resources.
As others have said-- the more colonies your run the more time mgt. and prioritizing of jobs becomes essential. While you have smaller numbers really make an effort to try different techniques and pay attention to what is effective and efficient. get a good idea of what the max. a hive will give you in a year in your conditions. As you scale up you're going to lose a little bit per hive but having a benchmark will allow you to find the level where you can still get good production and manage the workload and assess what "model" works for you-- 100% from 100 hives, 95% from 300, 85% from 1000 . . .
For sure try to latch on with a commercial outfit in your area for a few days to see what they do, pick there brain about local conditions, flows, timing, variety between years, etc. Which races do/have they use(d) in your locale? Learn the tendencies of your different yards. Sites separated by a few miles can have different patterns of pollen and nectar availability. Do some sites tend to build earlier in the spring? produce more/better honey? require more winter stores/supplemental feeding?. . . Study these types of things while small, so you can understand the tradeoffs as you grow and have to prioritize jobs.