Sure!
My 300SD came with a brand new starter (BOSCH!) and new battery and 'new' autolite glowplugs.
Well apparently 3 starts on autolites caused them to burn out (haha) so I repaced those.
Anywho, working in an auto electric shop and diagnosing weak/bad starters/alternators I would say I could most likely identify these things.
Summer and winter each have their own problems. Summer (if your starter gets hot from exhaust/engine/whatnot temperatures) you can have problems. Winter, thick oils, not wanting to burn cold diesel, etc. will attack the winters "cold motor" performance. But this is usually also thrown in with weaker battery operation.
I glow my engine the same amount of time my chime for my seat belt goes (1.5-2 times the glow light time) when it is cold and it purrs up just fine.
I never have to crank a starter long...seeing a few melted down on the inside, I always take it easy. Usually you can hear physical slowing as the armature/field starts to generate heat and become unhappy magnetized wire.
You want to see a test of starters?
Take a look at a marine starter...simply..disgusting heh.
I like working starters though
my bug had one with problems where it would draw 1000+ amps while not actually turning over very well (acted like a weak battery)
Bad field I believe. But those are easy and cheap rebuilds.