Residual blocks with 1 layer per block?

Yes, referring to that.
The layers are defined like:

self.conv1 = conv3x3(inplanes, planes, stride)
self.bn1 = norm_layer(planes)
self.relu = nn.ReLU(inplace=True)
self.conv2 = conv3x3(planes, planes)
self.bn2 = norm_layer(planes)

If its just about getting the right shape of out, one could replace it with a single convolution:

conv = conv3x3(inplanes,planes,stride)

no?
But you mean the fact that there is a nonlinearity ReLU in between changes that?

Best, JZ