I use Sleeve City 5mil and oversized 5mil outers for all my single, gatefold, and trifold jackets, and I have for years. I have some 5000 LPs (including many box sets that don't count towards the outer sleeved records). The outers take up extra space but are worth it.
Ask me about records jackets with ring wear....oh, wait, no, don't...I don't have that issue. :)