To make an obvious point, EI and gamma are related, and gamma in turn is related to developing time. For example, here are some results for Neopan 400 developed in Fujidol-E 1+1 (a PC developer) from the Japanese magazine 'shashin kogyo', September '98 (time/gamma/EI):
4"/0.45/160
5"30'/0.55/400
7"/0.66/800
10"/0.88/1250-1600
The usual recommendation for a condenser enlarger is a gamma of about 0.45, for a diffused light enlarger a gamma of about 0.55. But of course in practice there are many individual factors that enter in to determining a personal EI and developing time: camera/enlarger/lens flare, developer, agitation technique, etc.