A Page Constructed without Subtemplates

tpl.html
tpl_1.html

page2.html is the same as page3.html, however it is implemented in the usual way, without templates. After studying how both of them are implemented, try to make a small modification in both of them and see which one is easier to be modified.

tpl_2.html
tpl_2_1.html
tpl_2_1
content
tpl_2_2.html
tpl_2_2
content