Might sound a silly question but I wonder what the various speed range is for each gear and in getting to them are you pushing up to maximum revs? I used to be able to find information like this in a cars specifications on a relevant manufacturers website or handbook but cannot find anything except specs for gear ratios.
I've checked the manual but can't find anything in there, also Googled etc online.
I've done about 2,000 miles in my 2016 model Jazz Mk3 and at first found it terribly hard to use the gearbox properly, especially around the peak district up steep hills. I now ignore the change up/down gear indicators most of the time and also change up or down the gears missing out the intermediate gears as and when it feels appropriate. I especially like to go up from 4th straight into 6th, likewise changing down from 6th to 4th or even to 2nd depending on circumstances. I also find going from 6th to 3rd quite useful at roundabouts.
Like I said I found it really hard to get used to the gearbox and the closeness of the ratios but finally I'm feeling I'm happy with the gearbox.