For me, I don't really care much about the length, I will read and subscribe to your comic if I saw something interest after scrolling through.
<Warning: philosophy comment>
What's the focus for your project? 'Fame' or 'just because'?
If you want to make some fame, become famous, then do what can be sell.
Attention span is way too short nowaday (as you already saw in some replies above). If you can't make something interesting within a singe page (high enegy content and/or good artwork), and trying to do a long story with slow pacing like a traditional novel or story focus comic, then you're a goner.
For example: My comic, the first 24 pages only focus on characters and nothing really happening, if you can't stand it then you got my point. I'm currently working on the prologue to fix this problem.
But if you just want to do something for fun, because you love doing it, then just do whatever you want.
Some people will love your comic/novel no matter what you do.