Subjunctive in past

Bonjour Eugene,

The use of Le Subjonctif Passé stresses the importance of having the task completed by a certain point (i.e. finishing one's exams) before being able to do "tout ça" (i.e "se la couler douce dans un parc avec un bon roman, tout en sirotant un jus de fruits bien frais"). Using Le Subjonctif Présent would focus more on the process of taking the exams as if you're relating a random fact.

I hope this is helpful.

Bonne journée !