There are advantages to both ways:

Some people like the tools in Excel, like the ability to copy data across columns (when the amount is the same every month).

You can also create a second Excel sheet linked to the first one with a calcuation (previous amount * 1.05 for example) where needed.

However the tools to enter percent changes from current actual, or to distribute an annual amount across the months are not so easy to duplicate, so if you like these, your temporary database for budgeting should work well.