If the whole stage is only one beep of the timer, then there wouldn't be 4 strings. Perhaps 4 shooting positions?
The short answer to your question is no.
Is this a stage you shot or one you are designing?
Okay, yes. It would be 4 shooting positions. I misconstrued different shooting positions as strings. I take it each string consists of another start of the timer.
It was a stage I shot at a local league shoot. Our league is based on IDPA rules.
The stage went like this: A dark stage using a flashlight, we are standing at position-1 and draw, light the flash light and shoot 2 targets each that are side by side 5 yards out, then while moving to position-2 engage 2 more targets 2 times each, advance to position-3 and shoot 2 more targets side by side with 2 shots each, reload, then while backing up re-engage position-3 targets with 3 shots each. The targets that were "shot twice",more like best 2 hits scored, we were allowed to shot them Standard Vickers(as many times as we wanted), but the 3 shots on each target at position-3 while backing up we were limited to 3 shots only(Limited Vickers). I took an extra shot and received a procedure.
I can't recall ever shooting a stage that switched up like that. In skimming over the course description, I read unlimited shots for the first 3 positions and didn't catch the change to Limited Vickers for those last shots backing up. I'm at fault for skimming and not pouring over the details. I shouldn't have missed that. Lesson learned, and I won't let that happen again. I can't recall shooting a stage like that before in IDPA and kind of felt like it was a "gottcha". Although, I don't believe that was his intention.
So my question, is it allowed to switch form Standard to Limited Vickers in the same stage with only one start of the timer? I'm going to say no, because it was only one string, as you both point out. I didn't realize a "string" was a restart of the timer. I thought it was re-engaging from the new position.
What do you think?