Time is more relative than that, and is open to interpretation.
If you are roleplaying every day as though it 'were' everyday, 1 RL week might be no more Layo-time than 1-1.5 IC Weeks, or you could go the full 4 months if you are talking about the time in between something like Quest Sessions.
Remember, this goes in regard to RPing age and such.. some characters when created a year or more ago, were like 18, and now would be in their late 20s, early 30s..... but if you went 'exactly' by the running clock in the layo world, those characters would be in their late 60s-70s, so how is that realistic?
So time is relative to your needs, if you want 1 RL week to only be 1 IC, then RP that way, if you want 1 RL week to be 4 IC months, then do that, or some pick inbetween.