Free roam babies??

My son is 19 months and I let him roam as often as I can. He’s out exploring probably a 4 hours throughout the day. 2 hours in the morning and 2 in the afternoon/evening? Is that enough? I of course have to keep a close eye on him the whole time. We have baby proofed the best we can for now. He goes In his playpen while I take a bath or need to get some major cleaning done. He hangs out in his high chair for a good hour during breakfast and dinner. Does anyone let their little one roam as often or more often than I do? He’s been getting better at learning what he is not supposed to touch or what areas to stay away from.