That's the thing with C-drama platforms. Everything depends on the geo-location because of licensing issues.
Regarding the VIP system (iQiyi, WeTV, MGTV and Youku), all VIP subscribers get additional 6 episodes in advance. For subscribers in China, they have the further option of the VVIP where they get more episodes in advance and/ or other perks like the final 10 episodes (or so) get released immediately. The timing delay between international and China platforms is usually due to the subbing process.
Few other things to take note of would be that not all dramas are treated equally. Dramas that are popular or highly anticipated, featuring popular or famous cast, or generally well-accepted genres (eg rom-coms, certain historicals) would get released faster and with subs. If you noticed, obscure productions or generally Republican-era dramas either get delayed or not released internationally or subbed at all.
Regarding the different platforms, iQiyi and WeTV provide subbing services while MGTV (Mango TV) provides very limited shows with subs where sometimes those subs are machine subs. Youku also has the same problem. However I noticed lately, since many anticipated dramas are distributed by MGTV and Youku, the subbing situation has improved either via independent mainstream subbers (YoYo Channel, Viki) or the international channels of those platforms (Youku YouTube channel). This is the case currently with Word of Honor, Storm Eye and Rattan, just to name a few. The speed of subbing and release has improved markedly as well, probably due to the popularity of the dramas.