Like Jack says Leenia it really depends where you are starting from and where you are going. If it is from Edinburgh and you are heading towards the Highlands in general then there is no need to go via Glasgow. You could head towards Stirling and into the Highlands from there. If you are heading towards the Loch Lomond and far south-west of the Highlands then it probably is easier and quicker just to go right through Glasgow. It is motorway all the way through and easily navigated outside of rush hour times.