A number of proposals are flowing back and forth.
There are two principles involved here. The first principle is reflecting the size of the parties. The second principle is trying to be respectful of all members on the committee; they all prepare equally and presumably should get at least some opportunity to have a question in before you go to another round.
I'm using finance committee experience. Our finance committee experience looks very similar to yours in the first round, but in the second round we then go Liberal, Conservative, Bloc; then we go Liberal, Conservative; then Liberal, Conservative; then we go NDP. The reason is that you essentially then get through all the members of the committee and treat all members of the committee with some equality and also reflect their status in the House.