Buy a used 36" commercial walk behind. Far far superior cut to lawn tractor or RER and much faster.
I maintain 17 properties and they are all small postage stamp lots <1/4 acre. I run a Snapper pro 36" WB with a sulky and I can knock them out in no time. I almost double my productivity compared to running a 21" push mower.
I bought mine used about 3 years ago for $1k. I plan on buying a brand new hydro model in the spring.
I recently helped my uncle prep his yard to aerate and overseed and it needed to be cut shorter before we aerated. He has a lawn tractor and was amazed when it only took me about 20 minutes to cut his yard that usually takes him 35-40 minutes with his rider.