There is a limit of 400 VM per lab that applies no matter which VM size is selected for the lab.
There are also a few other limits that you need to be aware of:
* All Azure subscriptions have an initial limit that restricts how many VMs you can create. You will need to submit a support ticket to have this limit raised.
* You also need to ensure that if you're creating a large number of VMs, that you create your labs in a region that has sufficient capacity of the VM size that you need. This is especially important if you plan to use GPU sizes.