When the leaves wrinkle like is shown in your 3rd pic, I think it needs water. When the leaves have scars, holes, and marks like is shown in your other pics, I'd say it's been physically damaged. No big deal and nothing to do but maybe have a talk with the cat and avoid banging into the plants with anything. :O)

Watering once a mo is likely too little. And damage looks mechanical - agree with iochroma and party_music.

In last 3 pics, I see some gravel - but looks like just a topdressing. It is good for topdressing, but too large for potting mix. Really wondering about your mix, what is visible in previous photos, looks quite peaty. If so, it may be hydrophobic from watering so rarely. But I am looking only at the photos, and they do not show potting mix well. Can you post better, clear close-up?

That 1st pot looks very deep, and I wonder if it has drainage holes - or is it just a photo?

I do have a cat! He never ever bothers plants, but my roommate's cat does. And when I first looked at the marks on the large plant, in the second photo, I thought she must be the culprit. (Cats!! haha) But I'm surprised that all of the brown damage could be scarring from being jostled. I didn't realize they were that sensitive!

Do you think the leaves flopping over and curling up is from too little water as well?

Rina_Ontario, the plant in the last 3 pics does have a gravel topdressing. Underneath is a chunky cactus/succulent mix. I don't think it is that peaty, it has a lot of bark in it, but here is a pic so you can see:

All of my pots have drainage holes. :)

With really chunky mixes, how do you tell when it's time to water? They dry out quickly at the top inch or two, so I have a hard time telling by sticking my finger in.

That mix looks better than I thought :)

Many ppl keep their succulents in more organic mixes, and seem to have np with them. So I do not want to say much...I use very inorganic mix, made of grit, perlite and very little turface. That is mix I use for all my succulents.

Yours has bark and looks like some soil in it - easy way to check it for moisture would be using bamboo or wooden skewer (or chopstick, or thin stick or pencil - as long as it is wood). They could be inserted deep into pot to see if most of the mix has dried up.

I never checked just the top inch r 2, but always far/deep into pot.

'Chunky' mixes will drain up much faster, and depending how much more water-retaining (as soil could be) material there is, it will dry up faster or slower. Overall, I believe that Sans like bit more frequent watering, but should not be overwatered just the same. I water mine approx. 1x/10days or so. More often if outdoors during warm months.

Leaves curl if not enough water, usually along the leaf, not across (not sure if you know what I mean). Floppy leaves could be from over- or under-watering I think. See what others say...

Agreed with above comments. Once damaged the Snake plant doesn't show it soon, leaving many to believe it is okay. Then a month later, you see what yours looks like. Damage will never repair itself but will out grow it with new leaves and pups (new young plants). There are many factors that can cause a plant's demise. Mostly keep warm, out of drafts and all the bright light they can get. With warm weather (80's to 90's) they require all the water possible. I have seen some sitting in water all the time! Most people don't keep their house that warm and hope you can take them outside for summer vacation.

A large well grown Snake Plant can take a lot of abuse being in darkness and little water and even temps in the 50's, but if something does go wrong then it will advance rapidly.

I've never had much success with Sansevieria. I do have some S. cylindrica that I've kept alive for some years. Though, when I bought them they were individually rooted leaf cuttings and eventually they pupped and the old leaves died so what I have sort of reverted to a more juvenile forum.

In my limited experience with other Sansevieria I let them dry out too much. Based on how my now deceased Sansevieria looked and yours looks I agree with the others that you probably aren't watering enough. I don't think they like to be treated like a xerophytic succulent and prefer a soil mix that is kept slightly moist all the time. The soil mix in your pic looks good for that. You probably only need to water it a bit more.

Seems I've received some hostility for offering advice. We can learn from each other's failures. I don't need to be an expert, full of success, to know something worth sharing. Besides that, me offering advice didn't take any opportunities away from those more experienced with the plant to offer advice. Surprisingly I'm not so great at caring for Sansevieria. Though, for a lot of people it is easy to grow, the plant's needs don't work so well for me so with the current exception of S. cylindrica I don't have any.

Polypompholyx, Keep on posting. It's up to us to decide who's giving the best advise. I still have my problems just as everyone here does. If anybody wants to hear my 2 cents it out there and about all it's worth. What works for one person may not be right for another but I like to hear all sides and make my own mind up.

Poly,

I'm sorry to learn you've incurred hostility for trying to help. Can't imagine why & regret learning we've got participants like that.

I can't grow any type of Sans Hahnii types. I've bought dozens and dozens, and tried all types of soil from organic to gritty. They all rot and fall apart

Manuel, Start with the most common and strongest hahnii. The regular green. Any soil as long as you keep it on the dry side. Water from the bottom tray and remove any sitting water after 10 minuets. You'll fill the pot being lighter when dry. Try to keep warm, bright light is an good option. The brighter the light the better for the plant.

I remember you having some Gold Hahnii which is one of the fussier types. Remember you're not alone. I have killed my share also. During winter season is my worse time of year.

Stush2049 Pitts. PA, zone 6 : I won't buy them anymore. I figure I have lots of other healthy types. Some plants just aren't for us

Wisdom beyond your age. Wish I has such will power.

Love all the comments and helpful information, thank U all, and the pics are the best