As with all other movements/zones, you can increase success by increasing the frequency. eg. If you are doing two traction training a week, you can increase it to three, you can put the pull-up sets at the beginning of the traction training. If the arms are weak, separate training methods can be applied for them. You need to solve your weak side.
Even the mentally retarded types can do pull-ups, they know neither technique nor periodization; you (ie here) as above-average people in society, you can listen to the science of training instead of listening to those types.