This can be an expected trade-off between length and throughput.
For ligation sequencing kits, 0.2pmol of processed DNA should be taken into the sequencing adapter ligation reaction.
Please note that the mass corresponding to 0.2 pmol varies depending on the fragment length. Please use this calculator for mass-to-mole conversion.
Compared to short DNA, long fragments tend to have lower elution efficiency from the SPRI beads, require more time to present to the pore due to the stoichiometry, and appeared to have a lower success rate of pore unblocking.