> With regard to using screen readers, do I need to use multiple screen readers if they differ?
Unfortunately, they all have their own quirks. Alt tags and other basics that are built into HTML should be pretty simple and consistent between screen readers. More custom things like modals and JavaScript interactivity and also random things you'd expect to be simple can be a headache though and require you to research what quirks screen readers have (random example: https://www.powermapper.com/tests/screen-readers/labelling/i...). It's very similar to how IE, Firefox and Chrome can render and behave differently on the same web page.
If you're testing on one screen reader though, you'll still be doing better than most and it'll catch a large portion of potential problems. It'll help with your alt tag dilemma as you'll experience first-hand how annoying useless alt tags are even if big websites are using them.
https://en.wikipedia.org/wiki/Web_accessibility#United_State...
> With regard to using screen readers, do I need to use multiple screen readers if they differ?
Unfortunately, they all have their own quirks. Alt tags and other basics that are built into HTML should be pretty simple and consistent between screen readers. More custom things like modals and JavaScript interactivity and also random things you'd expect to be simple can be a headache though and require you to research what quirks screen readers have (random example: https://www.powermapper.com/tests/screen-readers/labelling/i...). It's very similar to how IE, Firefox and Chrome can render and behave differently on the same web page.
If you're testing on one screen reader though, you'll still be doing better than most and it'll catch a large portion of potential problems. It'll help with your alt tag dilemma as you'll experience first-hand how annoying useless alt tags are even if big websites are using them.