Whilst it is perfectly possible to get good combs this way, you need to be paying a lot of attention during the process. You must ensure the hive is level from side to side, as the bees will draw down vertically. You must straighten out any wobbles before these are propagated through adjoining combs. Be aware that in natural circumstances, bees like to put in a few curves as this strengthens the comb. You also need to be careful not to hold the frames horizontally until the comb is attached at the sides (and preferably the bottom too) as this can lead to a nasty collapse.
There is a technique to handling frames: To see the opposite side of the frame, while holding the frame by the lugs, raise your right hand until it is above your left hand and rotate the frame like a hinged door until the opposite side is in full view. Then bring your right hand down level with your left. The frame will be upside down in your hands with the reverse side facing you.
When I got my flow hives last year I read up about foundationless frames because I was new to beekeeping. Advice I read was to alternate foundationless frames with frames with foundation when getting started. The bees were then more likely to build straighter comb. So far this has been the case. As a beginner I do feel more confident inspecting a frame reinforced with wire, but I am getting better with the technique of holding the frame like a turning the page of a book but it does take practice.
Meeting Address: Doncaster Secondary College, 123 Church Rd, Doncaster 3108