Spot on Gavin, it will! I think probably all learners feel they ‘plateau’ (or discover the treacle sea 
) at some point, and which point that is* will vary (I say this in the singular, but that doesn’t rule it out happening more than once!)
A very similar point was raised in the thread I’ve linked to below and as you’ll see reading through it, these situations are never ‘just me’ ones!