Yes I think they would like to keep a grass practice field but that may be a luxury they can't afford. We played on grass at Northwestern in 2016. I'm not sure it has happened since then. Turf does get hot in the sun. The covering of the IPF would at least keep the sun off. If they absolutely wanted to work out on grass, there is the grass practice area just to the north that U-High uses.Apparently, the new generations of artificial turf don't increase injuries as in the past. However, are they as cool to practice on as grass in the middle of summer. Illinois still has grass practice areas.
Northwestern would be the most recent, I think.I haven't heard of any. MVFC and EIU are all turf. I can't even remember the last time we played on grass.