Not to drift to far afield, but you're citing bits of well known history in the army's of the British Empire (it's an interesting history but not applicable to this thread) and I'm simply saying none of that holds any sway over modern day users of Lee-Enfields or other rifles being discussed.
Just like the American soldier of WWII would have little reason to top off an enbloc.
Those that use these rifles in 2021 can of course use them as they please. Using them in 2021 is really what the thread topic is about and we need not be limited by what was practiced under war constrained (materials and manufacturing) UK supply chains.
Wartime managers were terrified in the early to mid 20th century of soldiers burning thru large amounts of ammo. America shelved that fear by supplying HUGE amounts of loaded belts and enblocs to our fighting men, thank goodness.
Members of this forum will have to look at their supply of ammo and magazines and plan their work accordingly
ETA: putting 10 rounds in the gun is considerably faster via mag change vs two chargers for me and others I know that use Lee-Enfields quite a bit. I'm sruprised that you find chargers "much faster" than a mag change. I'd love to see you using chargers I might learn something.
And I even polish some chargers smooth and practice manipulation with dummy rounds in search of "speed"
I have mags that have been stored fully loaded for decades that still function 100%, maybe I'm just lucky.