All of this is made redundant by just... knowing this is how clocks work.
If you don't have a seconds hand/counter, you can't predict how many seconds are left in the current minute. If it's 11:45:01, it's 11:45 without seconds. If it's 11:45:59, it's still inside the minute-long interval known to everyone as 11:45. The clock can always be one second away from flipping to the next minute. I just mentally subtract one minute if I'm actually planning on being somewhere down to the fraction of a minute, and planning what I can do beforehand. Mentally subtracting 30 seconds is not any easier.
I don't see this as even having some kind of gimmicky benefit...
If you don't have a seconds hand/counter, you can't predict how many seconds are left in the current minute. If it's 11:45:01, it's 11:45 without seconds. If it's 11:45:59, it's still inside the minute-long interval known to everyone as 11:45. The clock can always be one second away from flipping to the next minute. I just mentally subtract one minute if I'm actually planning on being somewhere down to the fraction of a minute, and planning what I can do beforehand. Mentally subtracting 30 seconds is not any easier.
I don't see this as even having some kind of gimmicky benefit...