I think this is a very good idea. 
Every component not necessary has to be switched off, I guess there are some more - additional to the digitizer.
(I used a phonepad7 from Asus for a long time, of course different hardware (Atom processor from Intel) with Android. In the beginning I charged it every 5-6 days, after 4 years of usage the battery needs to be charged every 2-3 days. These values will probably never be reached with our much more powerful processor)
Every component not necessary has to be switched off, I guess there are some more - additional to the digitizer. (I used a phonepad7 from Asus for a long time, of course different hardware (Atom processor from Intel) with Android. In the beginning I charged it every 5-6 days, after 4 years of usage the battery needs to be charged every 2-3 days. These values will probably never be reached with our much more powerful processor)