The Zettelkasten community is proud of their self- developed tools like Obsidian, Emacs org-mode and Cherrytree. The promise is that creating a digital only knowledge base is highly efficient. To investigate the claim in detail the following Spreadsheet might help:
The user has to enter some information like writing speed and the amount of characters and then the spreadsheet will determine the estimated amount of minutes for each day. In the concrete example the analog Zettelkasten will occupy 2 minutes fewer than the digital version.It is more productive to create analog notes than typing the information into Obsidian.
But let us slow down the situation a bit and explain what the user of a zettelkasten is doing usually. He has to write of course new cards to add content to the system. Its up to the user how many cards he creates each day. This will affect how the note box will look in 6 months or in 12 months. More added cards per day will result into a larger and more interesting note box and vice versa.
The promise of digital note taking is, that it is pretty easy to write new cards. The assumption is that the computer keyboard in combination with an advanced GUI software is able to reduce the amount of time to zero. But this is not the case. Typing in something and clicking on all the drop down menus will require a certain amount of minutes. In the concrete example, the user has to invest 12.5 minutes each day for updating the digital Zettelkasten. After only a year the total amount is 12.5*365=76 hours. That means the user has to use the computer keyboard over endless amount of hours only to add some small piece of information into the digital knowledge base.