Is it just me, or has this problem gotten worse recently? A few days ago I had a list of recent lessons right at the top of the /series page, but now that page doesn't even show series progression anymore. Unless you know the link Martin shared, it looks like you have to individually check each series now.
I don't blame Laracasts for uploading sporadically, but because we don't know the schedule it should be as simple as possible to check for new lessons. Ideally, this might look like an automated RSS feed (obviously without the video itself), or maybe the ability to follow a series to get notified, but the least you could do is avoid making it harder to check than it has been in the past.