Yeah sounds like need to remove them as as targets and just observe the values. After all, the alerts are there to tell you aren't meeting your target.
I can't see how you can do it any other way than Tim has suggested. If you don't want to see, hear, or feel any alerts during your intervals then there probably is little point in having them. Too be honest, if you are constantly seeing them then you either need to work on developing a 'feel' for the pace rather than chase numbers, or make the range wider to accept your fluctuations.
I know they can be turned off on some Garmin devices (Edge ???) and it seems like such an obvious option to have. Especially since they're so intrusive, blocking the screen and vibrating like crazy.
And my feel for the effort is just fine, thank you. Much better than Garmin detecting changes in running pace for shorter intervals ;)
Oh well, have to continue making noise about this feature I guess.
The thing is with intervals that have a pace target is that it determines whether you're in the range or not is based on Lap Pace. So unless you start to pick up the pace as soon as the warning beeps that alert you that an interval is about to start you will almost certainly get a behind pace alert after a few seconds into it even if you're already on the pace.
I rarely use a pace target for anything less than 800m but I'm trialing the new adaptive HM plan and yesterday's workout had 1' and 30" intervals with pace targets and it did get annoying on the couple of repeats I did without ramping up going into them and with these plans you can't edit the workout so I was stuck with the targets.
On the one hand I can understand wanting the option, but on the other there's a pretty simple work around.