when do you push out your soft freeze in lane?

in an even lane, it isn't often the case where i can get a hard freeze to deny champions like irelia or nasus without sacrificing too much health

i am, however, often able to zone them off the creeps here and there though, which lets me build up a large stacked minion wave after a soft freeze

but after it pushes out i'm often stuck in an unfavorable position

the wave is often so large that they're under their turret for quite some time and able to sustain back up quite a bit the turret does not clear my minions quickly enough that it stays under their turret for the next wave or two sometimes the wave is cleared at a poor time such that the next wave of my minions meets theirs at a position in lane that's very close to their turret sometimes this even results in a free hard freeze for the other laner; the worst possible situation for me and lastly, if i'm in a backed up position for an extended period of time it becomes difficult to place a ward for when the lane pushes forward; it's also predictable that i'll eventually become vulnerable to a gank so it's quite possible for the enemy jungler to plan their route in advance

i'll add that i'm playing as riven against such sustain champions because i understand ranged champions have the option of harassing them under their turret, but this is more difficult as a melee champion (and any tips to do so as riven are also appreciated); i intend for my question to remain open though