If you have a Garmin head unit you can install XSS Buckets and/or the Xert Dashboard to free ride and fill the buckets to meet your recommended low/high/peak XSS and target Focus for the day (Rouleur = 6 minute power in your example).
Or regardless of head unit type you can free ride irregular intervals at or above your Focus Power target. For example, if your 6-minute power is X watts, ride intervals at or above that value with appropriate RIBs (rest-in-between) until you reach the recommend total XSS for the day (169).
An easy way to visualize this is to run Autogen which generates a simple workout that can be downloaded to a head unit. Or just note the watt targets for work and rest intervals and use that to guide your free ride. For example, 9 intervals of X seconds/minutes, at or above X watts, with X minutes easy rest-in-between.
For LIT days you want to spend the majority of your ride around LTP and avoid surges above TP which would raise Focus Type above Endurance and accumulate high/peak XSS.
For HIT days the contribution to low/high/peak strain from your intervals primarily follows this graph –
(Courtesy of Dave Brillhart on the FB users group.)
Other newbie tips posted here –
Onboarding steps for Xert trial users and newbies - General - Xert Community Forum