You say "time building" as though that is a worthy goal in and of itself- pumping up multi time. But what exactly is the value of this time building if it consists of riding around in the southeast watching waypoints float by with another person who is doing even less than you are? Do some engine out approaches in IMC. Riding around on an IFR flight plan with two engines is no harder than doing basic instrument training. Shoot as many approaches into as many oddball airports as you can, with an engine in sim-feather and nobody else helping. Other than that, maybe practicing VMC demos and doing air work. Just flying IFR in what amounts to $100 hamburger runs is useless. Be creative about your time and design a self-training curriculum that will challenge you.