Your plant looks great! I agree that the brown spots looks like damage rather than disease.
Most people kill their houseplants by overwatering so be careful.
I'm a lazy waterer and my plants get watered once every 3 or 4 weeks. But I give them a deep watering.
I've had my corn plant for almost 30 years and I've put it thru hell but its still growing. It likes bright but not hot light so a South window that gets hot sun is no good. I have mine in an East window. Every summer it goes outside for the summer. The only problem I've had is that when I bring it back in no matter how much I water & mist it the bottom leaves turn brown so I have to do some trimming. Maybe its the dry air? One year I put it in full sun and burned it to a crisp. Hey, edible corn plants like full sun so I thought this one would too.
I cut off all the dead leaves (there was nothing left but stalks) and sure enough new leaves appeared. Lesson learned. Now it goes out in a very shady part of the yard.
One time I only had West or South windows available so I stuck it in an Eastern corner with little light and it grew to over 6 feet tall but had very skinny stems and leaves only at the top. It reminded me of a palm tree. I had to prop them up with sticks. Well I got tired of this and cut the tops off and stuck them in another pot then cut the tall stems down to a foot tall and waited. I thought if the tops didn't root out I still had the stem potted with the roots so I'd still have the plant. The tops rooted quickly and the original pot with the stems leafed out so I ended up with 2 plants. I gave one away tho.
All this rambling on and on is to let you know these plants are hardy so chill out, relax and enjoy the plant!
