Dynamic Stealth DC Guide/Optional Rule

I've noticed that a lot of the time stealth during sessions tend to be more or less about rolling a skill check, and nothing much more. So, I came up with a guide for dealing with stealth segments during play that are a bit more dynamic than that. (Taking inspiration from hitman and similar games)

NPCs have four alertness states; Relaxed, Distracted, Investigating and Vigilant. For all of these, DC to muffle a sound (strangling somebody, knocking over dishes) is variable depending on how loud it is (Guns require special equipment). In addition to this, NPCs also have different levels of awareness depending on where they are looking. This rule takes into account four different "zones" of view - right in front of an NPC, "diagonally" in their near-mid peripheral vision, "side view" in their far peripheral vision, and behind them or otherwise out of view but still in their vincinity. What this means is that if they are looking away or are busy doing something, they'll be more difficult to sneak up on. If there are multiple NPCs looking in different directions, the highest DC is used for rolls.

Distracted - occupied with something, not suspicious; unlikely to notice anything; sneak checks only required when doing something brash or loud [Side or out of view requires no roll, DC 6 diagonal, DC 8 in front]

Relaxed - not occupied with anything, not suspicious; will not notice anything outside what’s directly in front of them; sneak checks are only required when moving in their peripheral view [Out of view requires no roll, DC 6 side, DC 8 diagonal, DC 12 in front]

Investigating - occupied with something, suspicious; will focus attention towards a particular area or thing; suspicious people investigating disturbance or distraction; sneak checks necessary when moving in their vicinity [DC 6 out of view, DC 8 side, DC 10 diagonal; In front is instant failure]

Vigilant - not occupied with anything, not suspicious; will actively use all senses to perceive things; usually alert or curious people; sneak checks will be necessary when moving in vicinity of them, increasing in difficulty [DC 8 out of view, DC 10 side, DC 12 diagonal; In front is instant failure]

NPC is trained to stand guard or monitor areas: +1 to all DCs

NPC is unusually perceptive: +1 to all DCs

NPC has special cyberware or technology dedicated to detecting intruders: +2 to all DCs

NPC is tired or otherwise mildly impaired: -1 to all DCs

NPC is inebriated or otherwise heavily impaired: -2 to all DCs

As per the book rules, no amount of modifiers should exceed -2 or +2.

As an example, if there's a trained guard on high alert, the PCs can smash a bottle nearby to have the guard investigate it, and have an easier time sneaking past them. Again, this is less of a new rule as it is a guide for setting DCs and deciding when you don't need the PCs to roll at all, but I hope it helps. Any feedback would also be hugely appreciated.