When you buy a workshop you greatly increase your farm. To fully understand how it works, let's look at the image below.
Without a worker whenever your towers go to rest they get 3 attacks per minute. If you buy workers, this amount can increase up to 113 attacks per meaning.
Let's take as an example a tower with fuel enough to do 660 attacks. If you do not own any worker, that tower will need 200 minutes to fully charge. I
If you on the other hand possess a Little Workshop with 2 workers (the one that costs 0.75 BNB), you will only need 94 minutes to complete the maintenance. This makes your towers recover faster and improves your rewards.
Workshops can change the game's strategy, allowing a substantial increase in daily rewards (considering you use the workshop to the fullest).
Workshops ARE LIMITED AND WILL NOT BE ADDED IN THE FUTURE.