I imagine that the high pressure combuster starts on the Electra were as chancy as those on the B707 anf DC-8. Some of our customers had them fitted to DC-8-40 and B707-400's. DC-8 stored the high pressure air in a chamber built into the top of the MLG oleo. B707 had separate bottles and L-188 I think, few were fitted with it, fiberglas spheres.
On a few occasions when tried on DC-8 and B707 they only worked half the time. Hung start with no backup air supply to motor engine was not good. I imagine the Electra was no better although the Allison was a lot smaller than a RR Conway even with its prop.
You are certainly right about the recovery time to recharge bottles, couldn't even use high pressure nitrogen to assist as you needed to be able to add fuel and ignition to combust the air to give it an energy boost for the start.