problem in defining pool ip addresses in the round robin manner

[h bagade]

Hi all,

I've noticed that there is no way to define pool addresses in the format of
networks when it is in the mode of round robin? Is this true? I want to nat
IP addresses in to a range of IP addresses in a round robin manner. In the
case of round robin I should try the ip addresses one by one on the right
side of nat rule which is not optimal in compare with if it could be defined
in network addresses!

for instance, I want to nat ip addresses from 192.168.0.0/24 network to the
range of 10.10.10.1- 10.10.20.20 ip addresses in round robin. In pf rule I
should list the ip addresses in range one by one like this:

nat on $ext_if from { 192.168.0.0/24} to any -> {10.10.10.1, 10.10.10.2,
...., 10.10.10.254, 10.10.11.1, ...., 10.10.20.20}

which number of ip addresses on the right side is more that 2550 which could
be reduced extremely by defining network addresses {e.g. 10.10.10.0/24,
10.10.11.0/24, ... }.

Is my understanding true or there is a more simple solution for this
situation?
Any comments or hints are appreciated.