I’m not an examiner but from publicly available documents it appears there are two routes applications can take
Digital route – this is by far the quickest – all the checks etc they do can be completed entirely digitally – you’ll know if you’re on this route if your application goes from Docs received to Approved – there will be no processing update, in fact the absence of a processing update is a good thing!
Manual route – if for some reason the application can’t be completed entirely digitally then it drops into the manual processing route – your update will go from docs received to processing – it’s then anyone’s guess how long it will take depending on what the issues are.
So I would say the longer your application remains on the ‘docs received’ stage the better as it shows you’re still on the digital route.
Anything can drop an application to the manual route – and apparently even requesting a call back about the application is enough – so unless it’s really urgent don’t contact them unless you really have to.