Opticians- Pupil Distance?

[Kiwi79]

Not sure if there are any opticians in the house but interested to get your thoughts on this.

I was measured up for some new glasses today and when it came to my PD this measurement came up less than I expected it to be. The guy used some type of hadn tool rather than a machine to measure it I had very nearly bought glasses online using my very recent prescription but the one bit i was missing was the PD. Lucky I opted for instore.

Previously I had gone online and read a few how-tos and I get a measurment. The one I got in shop was about 3mm less, I now realise that the guy in the shop had it on the money.

I tried later to focus on something about 20ft away mark a dot on the lense then did same on other lense and if the two converged supposedly it's correct. This matched what they had in the shop. However my real question is if your PD varies between say screen work where presumably it's narrower vs say long distance say driving how do you as an optician end up with a best of both worlds? 2 pairs of specs is not that practical or is that now the done thing where you are 8hrs+ at a monitor