Yes, the mainform uses all the forms that needs, the rest 24, use none.
So you implement all your programs in such simplistic design and every form is only invoked from the main form (and main form only) ?
That is perfectly ok if that works for your clients/programs.
Nope there is only one level of depth and proper coding. If for any reason I fill the need to use any other form then I know my design is wrong.
I'm perfectly ok with the fact that you seem to want to imply that there is something wrong with my design skills, but such remark (icw the one above) seems to suggest to me that there is missing something from yours. No offense.
When you write code you must think each unit as an island, it can fire a flare (event and event lists), to inform the islands interested in its affairs that something changed, but it can never reach out and touch other islands with out starting a war.
Indeed an island. Self contained and which can be invoked from everywhere in the application at any time (when required).
So in order to avoid (future) problems it is much better to avoid including other units inside the interface section of a unit (i have marked the exceptions to that rule).
In case you wanted to get your point across that DavidTh30's example works as intended then i guess you have made your point. But that point only works in practice for that particular example of simplistic (linear) design.