Let's see
Under the sample army section, a Late period Saxon Army is given as:
1 Shieldwall Companion
5 Ordinary Shieldwall
2 Irish Warriors Allies
2 Foot Skimrishers
If you are using 15mm, DBX basing, this translates to:
6 x Sp = 24 figures
2 x Wb = 6 figures
2 x Ps = 4 figures
total = 34 figures, or about a DBA army.
If you go 4 bases to a unit, then it becomes 136 figures, which is I believe fewer than a DBM/DBMM/FOG army?
In 25mm/28mm the recommendation is to use a 6cm frontage, so if you are using WAB basing you are looking at fewer than 60 figures?
If using Impetus just use 1 Impetus base per unit.