I remove the inner timing cover to get access to the timing chain, the crankshaft timing sprocket and nose bearing, the timing chain tensioner and the chain rubbing block (aka, slide rail).
The chain, sprocket, nose bearing, chain tensioner and rubbing block wear and this affects timing. The wear can be great enough that you can hear the timing chain rattle.
You can read about how I do this work here:
I made a short video summarizing the procedure that you will find here.
I will replace the crankshaft sprocket, nose bearing, chain tensioner, rubbing block and the internal components of the oil high pressure relief valve. I will post a separate write-up showing how I do that.