Thank you for your question!
The Gutenberg editor has the ability to save custom blocks that makes it easy to reuse that block in other areas of your website. Click on the block you want to reuse in your editor and select the More Options button, the three vertical dots.
A dropdown will appear and in there you will see the Add to Reusable blocks option. Click that to save your block and make it reusable. You can then add your saved block to a page by using the Add Block button and finding your block in the Resuable Blocks group.
I hope that helps make it easy for your to reuse your calendar block and please let us know if there is anything else that we can do to assist you!