Bro, for JBJ website, you may wish to assess the volume of water and heat load stated and compare to yours. In general, a chiller seems to overwork by kicking in frequently(like every hour) and take hours to cool your tank. The kick in frequency can attribute from heat load in your tank and sump and the hours to cool your tank is likely to tell you whether the chiller is being stretched.
I used to run my artica 1/5 for 2 ft cube with sump, it take around 30 mins to cool down the water and take easily 2 hours to kick in again. Of course, other factors do come into picture, such as weather, direct sunlight, poor ventilation, etc.
I think bro terry won't mind as he is being helpful. Getting to meet up with senior reefers, many will advice 1/4 for a 4 ft tank. and if possible, 1/3. If possible, some reefers like to go one level 1 up for chiller and skimmer. Hence, to answer your question , is not a must.
In this hobby, IMO, no definitely right or wrong(for certain case) but you face the music if you dont follow the follow....like skimmer, some reefers dont use them and their tanks are in good state.
We are here to share and not giving order....lol. The ultimate choice is yours. Happy reefing and enjoy the exciting in setting up...it is just the beginning....the never ending road.....unless....decom....and never look back....