I have used hand pushed reel lawn mowers for about 20 years now.  I have a SE Pennsylvania typical yard of a mix of fescues, bluegrass, zosia grass, white clover, red clover, and various weeds, I do not use any lawn treatment, managing the health of the lawn strictly by mowing height, timing of mowing and watering during extended droughts.  That's worked very well for me.  Especially in those full sun areas where the wonderful zosia grass can grow.  I have many shrubs, trees, and bermed somewhat steep slopes.  A full mow of my 1/5th acre property takes as much as 6 hours when the grass is most ragged, yet in high growth (late spring-early summer).  More typical time is 3.5 to 4 hours.  It's a two day job.  Once mowed the lawn looks great.  I cross mow about 1/3rd to 1/2 of it -- the most used part and the most visible part.  About 15,000 pedometer steps.