The number of users using the accounting program is not as relevant as you would think.
You are looking at it from the point of view that you are preventing basic users from changing previous financial years. That is one use of the lock date. Once you have “closed” the financial year and paid out the required VAT and Corporation etc taxes, you don’t want users making changes to previous financial years as this would affect your VAT and Corporation Tax figures which have already been submitted.
Another user case would be to prevent accidental creation/deletion/editing of previous years financial records to prevent discrepancies with tax calculated and paid.
So I could clone invoices for my clients from the previous financial years or I could clone a purchase invoice I made months ago to purchase the same items again. But I forget to update the date! Having the lock in place, shows me I am trying to update a previous financial year and I see this and click on today’s date accordingly. Cloning may not be the only area where accidental changes to previous financial years might ago, but is probably the most common one.
You want to be very aware that you are in effect altering a previous financial year’s transactions. Even though Manager does not use a formal closing procedure like old fashioned accounting programs where there was a whole process, you do actually need to “close” the previous financial year and have it “set” as otherwise what you have paid in VAT and Corporation Tax may no longer match what Manager says you owe. This is what the lock date achieves in conjunction with the start date.
It should be very rare that you need to change anything in a previous financial year (apart from year end accounting week). So why have the ability to accidentally alter your previous financial year. More than once, I have forgotten to update the date when cloning something.
It is good accounting practice to have a permanent lock date in place as 99.9% of the time you are only entering for the current financial year. It actually helps people who are not good with accounting to prevent them from making mistakes.