My dd is 11 weeks and i found she put herself on a mixture of 3.5 hr EASY and 3hr EASY. If she starts going longer between feeds, then extend, but if she is hungry at 3 hours then feed. My lo tends to do 3.5 hours morning time, then afternoon and evening 3 hours. I changed my naps to 2 x 2hrs and a catnap, to compensate for longer A times, she does about 1hr 40 mins, but again it depends on you lo. If your lo can handle longer A times then adapt your routine accordingly, but if its all going well and you aren't having any 45 min nap issues, then i would say stay with it until you lo starts to adapt.
Changing may give you all sorts of issues!!! I changed my routine and get 2 NW's now, but had to do something as the routine was lasting til about 9 at night!!! Just hope she adapts and extends at night soon.