Use of pilum with skirmishers

[Quintus Aurelius Lepidus]

or would it be more something like this:

These are javelin heads which armae is selling. they are 16 cm great. i'm wondering about the shaft though. I think total spear will be like 120 or 140 cm long or so.

But then I'm wondering whether you can actually put 8 or 10 of these in a quiver.

forgive me if you feel i'm going a little bit of topic.