This really depends on a lot of factors, e.g., company size, number of users, number of installed modules, number of transactions within each modules, etc. Also take into account company growth, which is dependent on many additional factors. Moreover, what happens after 3 years. If you are concerned that the growth might exceed the current configuration, you could opt for some orchestration/provisioning tools (e.g., Docker Swarm, K8s, Terraform), which allow you to implement e.g., auto-scaling, load balancing. That way your setup will always meet the demand. I hope this helps!