The impact of these is pretty huge. You need to give the defenders a chance to react. This doesn’t just siphon off money, it literally makes their infrastructure a LOT easier to kill. An ESS, mobile depot, MTU, current siphon, etc, they all have very significantly lower impacts, not just to the specific mechanics (ones that have no strategic or tactical significance) they impact, but to the scale that they impact them.
I would only expect to see them used in warfare circumstances where you control the space (ie your opponents either won’t undock or have evac’d the system). Basically it’s a “you can undock and fight us now, or you can say goodbye to your structure faster”.
You’re assuming they’re watching it 24/7. They aren’t… at least, not in every case. Nor should they be expected to (an assertion backed by CCP’s stance on vulnerability windows).
By giving them 5 hours to notice it on their own, they’ve time to respond. By giving them a notification 12 hours later, they’ve got something to point out to them that there’s a fight to be had. Failing both of these, they lose high power status on their citadel.
As for bubbles in HS/LS, I’d say “meh”. Let it happen there. Just make the anchor point somewhere specific to prevent interdiction, and make it not act as a drag/catch bubble.