As often as not, that's a result of shit infrastructure behind the Skype for Business deployment itself, rather than the client itself. There are a number of baffling restrictions baked into the server and protocol itself, and a real production-grade deployment is a byzantine mess that would give Cthulu nightmares.
It doesn't help that the client hasn't had much more than cosmetic changes in at least five years, and is largely abandoned for Microsoft's kludgey Slack competitor.
Not only is Sky shaky, but it's advertised as 'free as in beer', if you want to talk for more than 2 minutes you have to pay. Everybody wants to talk for more than 2 minutes.
The only solution on Linux that implements audio, video and screen sharing is Sky (http://tel.red/), and it's incredibly flaky.