Apple limits the number of Accessories a Thinka can control to 150.
However an accessories can be a lamp that has 4 lightbulbs, that can be switched and dimmed.
In this case, one accessory (the lamp) has 4 services (the bulbs) that have 4 group addresses (on/off set and listen, dim set and listen).
So in this case 1 accessory can have 1 * 4 * 4 = 16 group addresses. So the limit of 150 accessories in practice means you can have a multitude of group addresses.
It just depends on how you define an accessory.
If you need to control more than 150 accessories, you can use multiple Thinka's in the same network.