We have no deer but the squirrels and bunnies and gophers can be downright voracious in the succulent garden this time of year (7 months since it rained). Succulents are extra tasty to them because of the water content. Some observations...
The youngest, softest plants are the ones that get eaten first. A brand new installation is like a buffet to the mammals. Something about living the hard life out in the sun seems to toughen up plants and make them far less tasty. You can have two groups of plants growing side by side, all of them the same species or variety, and the squirrels will home in on the ones from this year, totally ignoring last year's group until those are all gone. The natural consequence of this behavior is that you gain a significant advantage if your plants survive a year or two. Of course that is only relative to the baseline voraciousness of the animals.
Also, the foraging here is quite seasonal, to the extent we have a rainy season and a dry season. Which makes sense because who would bother with a spiny succulent when there are tender young shoots sprouting everywhere?
It may help to pay attention to when the deer are most likely to visit, and have a drop-down layer of chicken wire ready. For temporary or seasonal overhead protection. I use chicken wire for the bunnies, which is foolproof when combined with a gopher basket below (basically a cylinder of chicken wire underneath the plant, with a tighter mesh). I will eventually remove the above-ground chicken wire once the leaves on those trees are above the bunnies' reach.
In every mixed buffet experiment in the garden, where I have left different plants out together in the same space, there are some plants which are extra tasty and disappear first. Even though the foraging might happen over the course of a few days, there's a clear order to their selection. Other plants must be bitter and they might make it through unscathed. This Echeveria is the #1 top choice on the patio among the squirrels, mice, and birds who visit looking for food.
A couple of consequences relate to this. One is that sometimes by losing plants you learn which ones made it, which can be useful to know. And over time the garden becomes a bit more long-lived. Also, you can intentionally plant things the animals do not like and thereby make part of your garden less appealing to them. My go-to in this category would be the succulent Euphorbias, which the animals might try but do not actually eat. Those are notoriously cold-sensitive so that's not a recommendation, it's just a practical example from zone 11.